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Citation: S.A. Etesami, and E. Asadi (2018), "Molecular dynamics for near melting temperatures simulations of metals using modified embedded-atom method", Journal of Physics and Chemistry of Solids, 112, 61-72. DOI: 10.1016/j.jpcs.2017.09.001.
Abstract: Availability of a reliable interatomic potential is one of the major challenges in utilizing molecular dynamics (MD) for simulations of metals at near the melting temperatures and melting point (MP). Here, we propose a novel approach to address this challenge in the concept of modified-embedded-atom (MEAM) interatomic potential; also, we apply the approach on iron, nickel, copper, and aluminum as case studies. We propose adding experimentally available high temperature elastic constants and MP of the element to the list of typical low temperature properties used for the development of MD interatomic potential parameters. We show that the proposed approach results in a reasonable agreement between the MD calculations of melting properties such as latent heat, expansion in melting, liquid structure factor, and solid-liquid interface stiffness and their experimental/computational counterparts. Then, we present the physical properties of mentioned elements near melting temperatures using the new MEAM parameters. We observe that the behavior of elastic constants, heat capacity and thermal linear expansion coefficient at room temperature compared to MP follows an empirical linear relation (α±β × MP) for transition metals. Furthermore, a linear relation between the tetragonal shear modulus and the enthalpy change from room temperature to MP is observed for face-centered cubic materials.

Notes: S. A. Etesami (University of Memphis) noted that "We added both melting point and high temperature elastic constants into material properties database for MEAM parameter development process."

LAMMPS pair_style meam (2018--Etesami-S-A--Cu--LAMMPS--ipr1)
Notes: These files were sent by S. A. Etesami (University of Memphis) on 23 April 2018 and posted with his permission. This version is compatible with LAMMPS.
File(s):
Citation: E. Asadi, M.A. Zaeem, S. Nouranian, and M.I. Baskes (2015), "Two-phase solid-liquid coexistence of Ni, Cu, and Al by molecular dynamics simulations using the modified embedded-atom method", Acta Materialia, 86, 169-181. DOI: 10.1016/j.actamat.2014.12.010.
Abstract: The two-phase solid–liquid coexisting structures of Ni, Cu, and Al are studied by molecular dynamics (MD) simulations using the second nearest-neighbor (2NN) modified-embedded atom method (MEAM) potential. For this purpose, the existing 2NN-MEAM parameters for Ni and Cu were modified to make them suitable for the MD simulations of the problems related to the two-phase solid–liquid coexistence of these elements. Using these potentials, we compare calculated low-temperature properties of Ni, Cu, and Al, such as elastic constants, structural energy differences, vacancy formation energy, stacking fault energies, surface energies, specific heat and thermal expansion coefficient with experimental data. The solid–liquid coexistence approach is utilized to accurately calculate the melting points of Ni, Cu, and Al. The MD calculations of the expansion in melting, latent heat and the liquid structure factor are also compared with experimental data. In addition, the solid–liquid interface free energy and surface anisotropy of the elements are determined from the interface fluctuations, and the predictions are compared to the experimental and computational data in the literature.

Notes: Prof. Mohsen Zaeem said that this potential was designed for accurately representing properties from 0K up to the melting point.

LAMMPS pair_style meam (2015--Asadi-E--Cu--LAMMPS--ipr1)
Notes: This file was sent by Prof. Mohsen Zaeem (Missouri S&T) on 12 April 2017 and posted on 5 May 2017.
File(s):
Citation: M.I. Mendelev, and A.H. King (2013), "The interactions of self-interstitials with twin boundaries", Philosophical Magazine, 93(10-12), 1268-1278. DOI: 10.1080/14786435.2012.747012.
Abstract: A new mechanism of adsorption of self-interstitials onto twin boundaries (TB) in face-centred cubic (fcc) metals is identified using molecular dynamics simulations. In this mechanism, self-interstitials are arranged in the twin boundary plane forming a previously unknown kind of self-interstitial cluster. The self-interstitial cluster in the twin boundary is bounded by lines of atoms under high hydrostatic pressure while the pressure inside the cluster is much smaller. The atoms in the middle of the cluster have hcp short range order rather than fcc. However, if a new self-interstitial cluster forms in the middle of a pre-existing one, then the atoms in the middle of the new cluster will have regular twin boundary coordination. As a consequence of the formation of self-interstitial clusters inside each other, TB can be powerful, non-saturating sinks for self-interstitials.

Notes: Update 2018-06-12: Publication information added.

LAMMPS pair_style eam/fs (2012--Mendelev-M-I--Cu--LAMMPS--ipr1)
Notes: This file was provided by Mikhail Mendelev (Ames Laboratory) and posted with his permission on 25 Jul. 2012. He noted that "This potential is an improvement of Cu1 from [M.I. Mendelev, M.J. Kramer, C.A. Becker and M. Asta, Phil. Mag. 88, 1723 - 1750 (2008).] to better describe stacking fault energies."
File(s):
Citation: M.I. Mendelev, M.J. Kramer, C.A. Becker, and M. Asta (2008), "Analysis of semi-empirical interatomic potentials appropriate for simulation of crystalline and liquid Al and Cu", Philosophical Magazine, 88(12), 1723-1750. DOI: 10.1080/14786430802206482.
Abstract: We investigate the application of embedded atom method (EAM) interatomic potentials in the study of crystallization kinetics from deeply undercooled melts, focusing on the fcc metals Al and Cu. For this application, it is important that the EAM potential accurately reproduces melting properties and liquid structure, in addition to the crystalline properties most commonly fit in its development. To test the accuracy of previously published EAM potentials and to guide the development of new potential in this work, first-principles calculations have been performed and new experimental measurements of the Al and Cu liquid structure factors have been undertaken by X-ray diffraction. We demonstrate that the previously published EAM potentials predict a liquid structure that is too strongly ordered relative to measured diffraction data. We develop new EAM potentials for Al and Cu to improve the agreement with the first-principles and measured liquid diffraction data. Furthermore, we calculate liquid-phase diffusivities and find that this quantity correlates well with the liquid structure. Finally, we perform molecular dynamics simulations of crystal nucleation from the melt during quenching at constant cooling rate. We find that EAM potentials, which predict the same zero-temperature crystal properties but different liquid structures, can lead to quite different crystallization kinetics. More interestingly, we find that two potentials predicting very similar equilibrium solid and liquid properties can still produce very different crystallization kinetics under far-from-equilibrium conditions characteristic of the rapid quenching simulations employed here.

LAMMPS pair_style eam/fs (2008--Mendelev-M-I--Cu--LAMMPS--ipr1)
Notes: This file was provided by Mikhail Mendelev (Ames Laboratory) and posted with his permission on 14 Oct. 2010. He noted that it is the Cu potential used for Cu-Zr in M.I. Mendelev, et al., J. Appl. Phys. 102, 043501 (2007) and M.I. Mendelev, et al., Phil. Mag. 89, 967 (2009), though the files are different due to transformations of the density and embedding energy functions which do not affect the pure element properties.
File(s):
Citation: X.W. Zhou, R.A. Johnson, and H.N.G. Wadley (2004), "Misfit-energy-increasing dislocations in vapor-deposited CoFe/NiFe multilayers", Physical Review B, 69(14), 144113. DOI: 10.1103/physrevb.69.144113.
Abstract: Recent molecular dynamics simulations of the growth of [Ni0.8Fe0.2/Au] multilayers have revealed the formation of misfit-strain-reducing dislocation structures very similar to those observed experimentally. Here we report similar simulations showing the formation of edge dislocations near the interfaces of vapor-deposited (111) [NiFe/CoFe/Cu] multilayers. Unlike misfit dislocations that accommodate lattice mismatch, the dislocation structures observed here increase the mismatch strain energy. Stop-action observations of the dynamically evolving atomic structures indicate that during deposition on the (111) surface of a fcc lattice, adatoms may occupy either fcc sites or hcp sites. This results in the random formation of fcc and hcp domains, with dislocations at the domain boundaries. These dislocations enable atoms to undergo a shift from fcc to hcp sites, or vice versa. These shifts lead to missing atoms, and therefore a later deposited layer can have missing planes compared to a previously deposited layer. This dislocation formation mechanism can create tensile stress in fcc films. The probability that such dislocations are formed was found to quickly diminish under energetic deposition conditions.

FORTRAN
Notes: These are the original files sent by X.W. Zhou (Sandia National Laboratory) and posted with his permission. C.A. Becker (NIST) modified create.f to include the reference in the generated potential files and the EAM.input file for this composition. These files can be used to generate alloy potentials for Cu, Ag, Au, Ni, Pd, Pt, Al, Pb, Fe, Mo, Ta, W, Mg, Co, Ti, and Zr by editing EAM.input. However, as addressed in the reference, these potentials were not designed for use with metal compounds.
File(s): superseded


LAMMPS pair_style eam/alloy (2004--Zhou-X-W--Cu--LAMMPS--ipr1)
Notes: This file was generated by C.A. Becker (NIST) from create.f and posted with X.W. Zhou's (Sandia National Laboratory) permission.
File(s): superseded


FORTRAN
Notes: The file Zhou04_create_v2.f is an updated version of create.f modified by L.M. Hale (NIST) following advice from X.W. Zhou (Sandia National Laboratory). This version removes spurious fluctuations in the tabulated functions of the original potential files caused by single/double precision floating point number conflicts.
File(s):
LAMMPS pair_style eam/alloy (2004--Zhou-X-W--Cu--LAMMPS--ipr2)
Notes: This file was generated by L.M. Hale from Zhou04_create_v2.f on 13 April 2018 and posted with X.W. Zhou's (Sandia National Laboratory) permission. This version corrects an issue with spurious fluctuations in the tabulated functions.
File(s):
Citation: Y. Mishin, M.J. Mehl, D.A. Papaconstantopoulos, A.F. Voter, and J.D. Kress (2001), "Structural stability and lattice defects in copper: Ab initio, tight-binding, and embedded-atom calculations", Physical Review B, 63(22), 224106. DOI: 10.1103/physrevb.63.224106.
Abstract: We evaluate the ability of the embedded-atom method (EAM) potentials and the tight-binding (TB) method to predict reliably energies and stability of nonequilibrium structures by taking Cu as a model material. Two EAM potentials are used here. One is constructed in this work by using more fitting parameters than usual and including ab initio energies in the fitting database. The other potential was constructed previously using a traditional scheme. Excellent agreement is observed between ab initio, TB, and EAM results for the energies and stability of several nonequilibrium structures of Cu, as well as for energies along deformation paths between different structures. We conclude that not only TB calculations but also EAM potentials can be suitable for simulations in which correct energies and stability of different atomic configurations are essential, at least for Cu. The bcc, simple cubic, and diamond structures of Cu were identified as elastically unstable, while some other structures (e.g., hcp and 9R) are metastable. As an application of this analysis, nonequilibrium structures of epitaxial Cu films on (001)-oriented fcc or bcc substrates are evaluated using a simple model and atomistic simulations with an EAM potential. In agreement with experimental data, the structure of the film can be either deformed fcc or deformed hcp. The bcc structure cannot be stabilized by epitaxial constraints.

Notes: This listing is for the reference's EAM1 potential.

EAM tabulated functions
Notes: These files were provided by Yuri Mishin.
File(s):
F(ρ): F_cu.plt
ρ(r): fcu.plt
φ(r): pcu.plt

LAMMPS pair_style eam/alloy (2001--Mishin-Y--Cu-1--LAMMPS--ipr1)
Notes: This conversion was produced by Chandler Becker on 4 February 2009 from the plt files listed above. This version is compatible with LAMMPS. Validation and usage information can be found in Cu01_releaseNotes_1.pdf. If you use this setfl file, please credit the website in addition to the original reference.
File(s):
Citation: Y. Mishin, M.J. Mehl, D.A. Papaconstantopoulos, A.F. Voter, and J.D. Kress (2001), "Structural stability and lattice defects in copper: Ab initio, tight-binding, and embedded-atom calculations", Physical Review B, 63(22), 224106. DOI: 10.1103/physrevb.63.224106.
Abstract: We evaluate the ability of the embedded-atom method (EAM) potentials and the tight-binding (TB) method to predict reliably energies and stability of nonequilibrium structures by taking Cu as a model material. Two EAM potentials are used here. One is constructed in this work by using more fitting parameters than usual and including ab initio energies in the fitting database. The other potential was constructed previously using a traditional scheme. Excellent agreement is observed between ab initio, TB, and EAM results for the energies and stability of several nonequilibrium structures of Cu, as well as for energies along deformation paths between different structures. We conclude that not only TB calculations but also EAM potentials can be suitable for simulations in which correct energies and stability of different atomic configurations are essential, at least for Cu. The bcc, simple cubic, and diamond structures of Cu were identified as elastically unstable, while some other structures (e.g., hcp and 9R) are metastable. As an application of this analysis, nonequilibrium structures of epitaxial Cu films on (001)-oriented fcc or bcc substrates are evaluated using a simple model and atomistic simulations with an EAM potential. In agreement with experimental data, the structure of the film can be either deformed fcc or deformed hcp. The bcc structure cannot be stabilized by epitaxial constraints.

Notes: This listing is for the reference's EAM2 potential.

EAM tabulated functions
Notes: These files were provided by Yuri Mishin and posted on 10 Dec. 2009.
File(s):
Citation: G.J. Ackland, and V. Vitek (1990), "Many-body potentials and atomic-scale relaxations in noble-metal alloys", Physical Review B, 41(15), 10324-10333. DOI: 10.1103/physrevb.41.10324.
Abstract: We derive empirical many-body potentials for noble-metal alloy systems in the framework of the Finnis-Sinclair model [Philos. Mag. A 50, 45 (1984)] which is based on a second-moment approximation to the tight-binding density of states for transition metals [F. Cyrot, J. Phys. Chem. Solids 29, 1235 (1968)]. The most important extension of the model is a simple incorporation of interspecies interactions which involves fitting the alloying energies. The importance of properly accounting for the local atomic relaxations when constructing the potentials is emphasized. The observed principal features of the phase diagrams of the alloys are all well reproduced by this scheme. Furthermore, reasonable concentration dependences of the alloy lattice parameter and elastic constants are obtained. This leads us to suggest that fine details of the electronic structure may be less important in determining atomic structures than are more global parameters such as atomic sizes and binding energies.

LAMMPS pair_style eam/fs (1990--Ackland-G-J--Cu--LAMMPS--ipr1)
Notes: A conversion to LAMMPS from MOLDY was performed by G.J. Ackland and submitted on 10 Oct. 2017. This implementation includes the short-range repulsion for radiation studies.
File(s):
Citation: J.B. Adams, S.M. Foiles, and W.G. Wolfer (1989), "Self-diffusion and impurity diffusion of fcc metals using the five-frequency model and the Embedded Atom Method", Journal of Materials Research, 4(1), 102-112. DOI: 10.1557/jmr.1989.0102.
Abstract: The activation energies for self-diffusion of transition metals (Au, Ag, Cu, Ni, Pd, Pt) have been calculated with the Embedded Atom Method (EAM); the results agree well with available experimental data for both mono-vacancy and di-vacancy mechanisms. The EAM was also used to calculate activation energies for vacancy migration near dilute impurities. These energies determine the atomic jump frequencies of the classic "five-frequency formula," which yields the diffusion rates of impurities by a mono-vacancy mechanism. These calculations were found to agree fairly well with experiment and with Neumann and Hirschwald's "Tm" model.

LAMMPS pair_style eam (1989--Adams-J-B--Cu--LAMMPS--ipr1)
Notes: cuu6.txt was obtained from http://enpub.fulton.asu.edu/cms/ potentials/main/main.htm and posted with the permission of J.B. Adams. The name of the file was retained, even though the header information lists the potential as 'universal 4.' Except for the first comment line, this file is identical to "Cu_u6.eam" in the August 22, 2018 LAMMPS distribution.
File(s):
Citation: G.J. Ackland, G. Tichy, V. Vitek, and M.W. Finnis (1987), "Simple N-body potentials for the noble metals and nickel", Philosophical Magazine A, 56(6), 735-756. DOI: 10.1080/01418618708204485.
Abstract: Using the approach of Finnis and Sinclair, N-body potentials for copper, silver, gold and nickel have been constructed. The total energy is regarded as consisting of a pair-potential part and a many body cohesive part. Both these parts are functions of the atomic separations only and are represented by cubic splines, fitted to various bulk properties. For the noble metals, the pair-potentials were fitted at short range to pressure-volume relationships calculated by Christensen and Heine so that interactions at separations smaller than that of the first-nearest neighbours can be treated in this scheme. Using these potentials, point defects, surfaces (including the surface reconstructions) and grain boundaries have been studied and satisfactory agreement with available experimental data has been found.

Moldy FS
Notes: The parameters in cu.moldy were obtained from http://homepages.ed.ac.uk/graeme/moldy/moldy.html and posted with the permission of G.J. Ackland.
File(s):
LAMMPS pair_style eam/fs (1987--Ackland-G-J--Cu--LAMMPS--ipr1)
Notes: This conversion was performed from G.J. Ackland's parameters by M.I. Mendelev. Conversion checks from M.I. Mendelev can be found in the conversion_check.pdf. These files were posted on 30 June 2009 with the permission of G.J. Ackland and M.I. Mendelev. These potentials are not designed for simulations of radiation damage.
File(s):
LAMMPS pair_style eam/fs (1987--Ackland-G-J--Cu--LAMMPS--ipr2)
Notes: A new conversion to LAMMPS performed by G.J. Ackland was submitted on 10 Oct. 2017. This version adds close-range repulsion for radiation studies.
File(s):
Citation: S.M. Foiles, M.I. Baskes, and M.S. Daw (1986), "Embedded-atom-method functions for the fcc metals Cu, Ag, Au, Ni, Pd, Pt, and their alloys", Physical Review B, 33(12), 7983-7991. DOI: 10.1103/physrevb.33.7983.
Abstract: A consistent set of embedding functions and pair interactions for use with the embedded-atom method [M.S. Daw and M. I. Baskes, Phys. Rev. B 29, 6443 (1984)] have been determined empirically to describe the fcc metals Cu, Ag, Au, Ni, Pd, and Pt as well as alloys containing these metals. The functions are determined empirically by fitting to the sublimation energy, equilibrium lattice constant, elastic constants, and vacancy-formation energies of the pure metals and the heats of solution of the binary alloys. The validity of the functions is tested by computing a wide range of properties: the formation volume and migration energy of vacancies, the formation energy, formation volume, and migration energy of divacancies and self-interstitials, the surface energy and geometries of the low-index surfaces of the pure metals, and the segregation energy of substitutional impurities to (100) surfaces.

LAMMPS pair_style eam (1986--Foiles-S-M--Cu--LAMMPS--ipr1)
Notes: This file was taken from the August 22, 2018 LAMMPS distribution.
File(s):
 
Citation: X.W. Zhou, R.A. Johnson, and H.N.G. Wadley (2004), "Misfit-energy-increasing dislocations in vapor-deposited CoFe/NiFe multilayers", Physical Review B, 69(14), 144113. DOI: 10.1103/physrevb.69.144113.
Abstract: Recent molecular dynamics simulations of the growth of [Ni0.8Fe0.2/Au] multilayers have revealed the formation of misfit-strain-reducing dislocation structures very similar to those observed experimentally. Here we report similar simulations showing the formation of edge dislocations near the interfaces of vapor-deposited (111) [NiFe/CoFe/Cu] multilayers. Unlike misfit dislocations that accommodate lattice mismatch, the dislocation structures observed here increase the mismatch strain energy. Stop-action observations of the dynamically evolving atomic structures indicate that during deposition on the (111) surface of a fcc lattice, adatoms may occupy either fcc sites or hcp sites. This results in the random formation of fcc and hcp domains, with dislocations at the domain boundaries. These dislocations enable atoms to undergo a shift from fcc to hcp sites, or vice versa. These shifts lead to missing atoms, and therefore a later deposited layer can have missing planes compared to a previously deposited layer. This dislocation formation mechanism can create tensile stress in fcc films. The probability that such dislocations are formed was found to quickly diminish under energetic deposition conditions.

FORTRAN
Notes: These are the original files sent by X.W. Zhou (Sandia National Laboratory) and posted with his permission. C.A. Becker (NIST) modified create.f to include the reference in the generated potential files and the EAM.input file for this composition. These files can be used to generate alloy potentials for Cu, Ag, Au, Ni, Pd, Pt, Al, Pb, Fe, Mo, Ta, W, Mg, Co, Ti, and Zr by editing EAM.input. However, as addressed in the reference, these potentials were not designed for use with metal compounds.
File(s): superseded


LAMMPS pair_style eam/alloy (2004--Zhou-X-W--Cu-Ag-Au--LAMMPS--ipr1)
Notes: This file was generated by C.A. Becker (NIST) from create.f and posted with X.W. Zhou's (Sandia National Laboratory) permission.
File(s): superseded


FORTRAN
Notes: The file Zhou04_create_v2.f is an updated version of create.f modified by L.M. Hale (NIST) following advice from X.W. Zhou (Sandia National Laboratory). This version removes spurious fluctuations in the tabulated functions of the original potential files caused by single/double precision floating point number conflicts.
File(s):
LAMMPS pair_style eam/alloy (2004--Zhou-X-W--Cu-Ag-Au--LAMMPS--ipr2)
Notes: This file was generated by L.M. Hale from Zhou04_create_v2.f on 13 April 2018 and posted with X.W. Zhou's (Sandia National Laboratory) permission. This version corrects an issue with spurious fluctuations in the tabulated functions.
File(s):
 
Citation: J.B. Adams, S.M. Foiles, and W.G. Wolfer (1989), "Self-diffusion and impurity diffusion of fcc metals using the five-frequency model and the Embedded Atom Method", Journal of Materials Research, 4(01), 102-112. DOI: 10.1557/jmr.1989.0102.
Abstract: The activation energies for self-diffusion of transition metals (Au, Ag, Cu, Ni, Pd, Pt) have been calculated with the Embedded Atom Method (EAM); the results agree well with available experimental data for both mono-vacancy and di-vacancy mechanisms. The EAM was also used to calculate activation energies for vacancy migration near dilute impurities. These energies determine the atomic jump frequencies of the classic "five-frequency formula," which yields the diffusion rates of impurities by a mono-vacancy mechanism. These calculations were found to agree fairly well with experiment and with Neumann and Hirschwald's "Tm" model.

Notes: Cross-element interactions were only considered for small (1-2%) impurity concentrations and use a generalized universal function.

LAMMPS pair_style eam (1989--Adams-J-B--Ag-Au-Cu-Ni-Pd-Pt--LAMMPS--ipr1)
Notes: These files were obtained from http://enpub.fulton.asu.edu/cms/ potentials/main/main.htm and posted with the permission of J.B. Adams. The name of the file was retained, even though the header information lists the potential as 'universal 4.' Except for the first comment line, "cuu6.txt" is identical to "Cu_u6.eam" in the August 22, 2018 LAMMPS distribution.
File(s):
Citation: S.M. Foiles, M.I. Baskes, and M.S. Daw (1986), "Embedded-atom-method functions for the fcc metals Cu, Ag, Au, Ni, Pd, Pt, and their alloys", Physical Review B, 33(12), 7983-7991. DOI: 10.1103/physrevb.33.7983.
Abstract: A consistent set of embedding functions and pair interactions for use with the embedded-atom method [M.S. Daw and M. I. Baskes, Phys. Rev. B 29, 6443 (1984)] have been determined empirically to describe the fcc metals Cu, Ag, Au, Ni, Pd, and Pt as well as alloys containing these metals. The functions are determined empirically by fitting to the sublimation energy, equilibrium lattice constant, elastic constants, and vacancy-formation energies of the pure metals and the heats of solution of the binary alloys. The validity of the functions is tested by computing a wide range of properties: the formation volume and migration energy of vacancies, the formation energy, formation volume, and migration energy of divacancies and self-interstitials, the surface energy and geometries of the low-index surfaces of the pure metals, and the segregation energy of substitutional impurities to (100) surfaces.

Notes: The cross-elemental interactions use a universal function designed to show trends across the metals and is not fitted for revealing compounds.

LAMMPS pair_style eam (1986--Foiles-S-M--Ag-Au-Cu-Ni-Pd-Pt--LAMMPS--ipr1)
Notes: These files were taken from the August 22, 2018 LAMMPS distribution.
File(s):
 
Citation: H.H. Wu, and D.R. Trinkle (2009), "Cu/Ag EAM potential optimized for heteroepitaxial diffusion from ab initio data", Computational Materials Science, 47(2), 577-583. DOI: 10.1016/j.commatsci.2009.09.026.
Abstract: A binary embedded-atom method (EAM) potential is optimized for Cu on Ag(1 1 1) by fitting to ab initio data. The fitting database consists of DFT calculations of Cu monomers and dimers on Ag(1 1 1), specifically their relative energies, adatom heights, and dimer separations. We start from the Mishin Cu–Ag EAM potential and first modify the Cu–Ag pair potential to match the FCC/HCP site energy difference then include Cu–Cu pair potential optimization for the entire database. The potential generated from this optimization method gives better agreement to DFT calculations of Cu monomers, dimers, and trimers than previous EAMs as well as a SEAM optimized potential. In trimer calculations, the optimized potential produces the DFT relative energy between FCC and HCP trimers, though a different ground state is predicted. We use the optimized potential to calculate diffusion barriers for Cu monomers, dimers, and trimers. The predicted monomer barrier is the same as DFT, while experimental barriers for monomers and dimers are lower than predicted here. We attribute the difference with experiment to the overestimation of surface adsorption energies by DFT and a simple correction is presented. Our results show that this optimization method is suitable for other heteroepitaxial systems; and that the optimized Cu–Ag EAM can be applied in the study of larger Cu islands on Ag(1 1 1).

Notes: 7 May 2010 Update: Reference changed from 'in preparation' at the request of Henry Wu (Univ. of Illinois).

LAMMPS pair_style eam/alloy (2009--Wu-H-H--Cu-Ag--LAMMPS--ipr1)
Notes: This file was provided by Henry H. Wu and posted with his permission. He also supplied a new file where the first line of the header was updated to reflect the publication status. The original file can be found here.
File(s):
Citation: P.L. Williams, Y. Mishin, and J.C. Hamilton (2006), "An embedded-atom potential for the Cu-Ag system", Modelling and Simulation in Materials Science and Engineering, 14(5), 817-833. DOI: 10.1088/0965-0393/14/5/002.
Abstract: A new embedded-atom method (EAM) potential has been constructed for Ag by fitting to experimental and first-principles data. The potential accurately reproduces the lattice parameter, cohesive energy, elastic constants, phonon frequencies, thermal expansion, lattice-defect energies, as well as energies of alternate structures of Ag. Combining this potential with an existing EAM potential for Cu, a binary potential set for the Cu–Ag system has been constructed by fitting the cross-interaction function to first-principles energies of imaginary Cu–Ag compounds. Although properties used in the fit refer to the 0 K temperature (except for thermal expansion factors of pure Cu and Ag) and do not include liquid configurations, the potentials demonstrate good transferability to high-temperature properties. In particular, the entire Cu–Ag phase diagram calculated with the new potentials in conjunction with Monte Carlo simulations is in satisfactory agreement with experiment. This agreement suggests that EAM potentials accurately fit to 0 K properties can be capable of correctly predicting simple phase diagrams. Possible applications of the new potential set are outlined.

EAM tabulated functions
Notes: These files were provided by Yuri Mishin.
File(s):
Ag F(ρ): F_ag.plt
Cu F(ρ): F_cu.plt
Ag ρ(r): fag.plt
Cu ρ(r): fcu.plt
Ag φ(r): pag.plt
Cu φ(r): pcu.plt
Cu-Ag φ(r): pcuag.plt

LAMMPS pair_style eam/alloy (2006--Williams-P-L--Cu-Ag--LAMMPS--ipr1)
Notes: This conversion was produced by Chandler Becker on 4 February 2009 from the plt files listed above. This version is compatible with LAMMPS. Validation and usage information can be found in CuAg06_releaseNotes_1.pdf. If you use this setfl file, please credit the website in addition to the original reference.
File(s):
 
Citation: X.W. Zhou, D.K. Ward, and M.E. Foster (2016), "An analytical bond-order potential for the aluminum copper binary system", Journal of Alloys and Compounds, 680, 752-767. DOI: 10.1016/j.jallcom.2016.04.055.
Abstract: Al-rich Al1−xCux alloys are important structural materials in the aerospace industry due to their high strength to density ratio. They are also emerging materials for hydrogen containing structures due to their potentially high resistance to hydrogen embrittlement. To enable accurate simulations of the mechanical behavior of Al1−xCux alloys that can guide material improvement, we have developed a high-fidelity analytical bond-order potential (BOP) for the Al-Cu system (the code is publically available in molecular dynamics package LAMMPS). The formalism of the potential is derived from quantum mechanical theories, and the parameters are optimized in an iteration fashion. The iterations begin by fitting properties of a variety of elemental and compound configurations (with coordination varying from 1 to 12) including small clusters, bulk lattices, defects, and surfaces. Following the fitting process, crystalline growth of important equilibrium phases is checked through molecular dynamics simulations of vapor deposition. It is demonstrated that this Al-Cu bond-order potential has unique advantages relative to existing literature potentials in reproducing structural and property tends from experiments and quantum-mechanical calculations, and providing good descriptions of melting temperature, defect characteristics, and surface energies. Most importantly, this BOP is the only potential currently available capable of capturing the Al-rich end of the Al-Cu phase diagram. This capability is rigorously verified by the potential's ability to capture the crystalline growth of the ground-state structures for elemental Al and Cu, as well as, the θ and θ′ phases of the Al2Cu compound in vapor deposition simulations.

LAMMPS pair_style bop (2016--Zhou-X-W--Al-Cu--LAMMPS--ipr1)
Notes: This file was taken from the August 22, 2018 LAMMPS distribution and listed as having been created by X.W. Zhou (Sandia)
File(s):
Citation: F. Apostol, and Y. Mishin (2011), "Interatomic potential for the Al-Cu system", Physical Review B, 83(5), 54116. DOI: 10.1103/physrevb.83.054116.
Abstract: An angular-dependent interatomic potential has been developed for the Al-Cu system based on existing embedded-atom method potentials for Al and Cu and fitting of the cross-interaction functions to experimental and first-principles data. The potential reproduces lattice parameters, formation energies, and elastic constants of the θ and θ′ phases of this system. It predicts the θ′ phase to be more stable than θ at 0 K but to become less stable at hight temperatures due to vibrational entropy. The temperate and entropy of this phase transformation are in good agreement with previous first-principles calculations [C. Wolverton and V. Ozoliņš, Phys. Rev. Lett. 86, 5518 (2001)]. The potential provides a reasonable description of the phase stability across the Al-Cu phase diagram, dilute heats of solution, and other thermodynamic properties. It has also been tested for generalized stacking fault energies in the presence of a copper layer embedded in Al. This configuration bears some resemblance to Guinier-Preston zones that strengthen Al-Cu alloys. The trends predicted by the potential for uniform shearing of this configuration are in agreement with results of first-principles density-functional calculations performed in this work. The potential is expected to be suitable for atomistic simulations of precipitation hardening of Al-Cu alloys.

Notes: Prof. Mishin requested the following be noted: There was a typing error in the original ADP paper (Y. Mishin, et al., Acta Mat. 53, 4029 (2005)). More information and a correction can be found in the FAQ.

ADP tabulated functions
LAMMPS pair_style adp (2011--Apostol-F--Al-Cu--LAMMPS--ipr1)
Notes: This file was taken from the August 22, 2018 LAMMPS distribution and listed as having been created by CV Singh (Cornell). The tabulated functions and their numerical derivatives appear consistent between this file and the tables listed above.
File(s):
Citation: X.-Y. Liu, C.-L. Liu, and L.J. Borucki (1999), "A new investigation of copper's role in enhancing Al-Cu interconnect electromigration resistance from an atomistic view", Acta Materialia, 47(11), 3227-3231. DOI: 10.1016/s1359-6454(99)00186-x.
Abstract: An explanation of why Cu prolongs the electromigration lifetime of Al–Cu interconnects in comparison to Al is provided based on atomistic calculations. Copper preferentially segregates to the grain-boundary (GB) interstitial sites. The overall GB diffusivity is reduced with Cu segregation at GB sites. Calculation results predict that in Al(Cu) lines, Cu will diffuse first, with Al diffusion essentially suppressed because of a higher diffusion activation energy. The activation energy for Cu incubation diffusion is calculated to be 0.95 eV. The predictions are in excellent agreement with experiments.

EAM setfl
Notes: al-cu-set.txt was obtained from http://enpub.fulton.asu.edu/cms/potentials/main/main.htm and posted with the permission of J.B. Adams.
File(s):
LAMMPS pair_style eam/alloy (1999--Liu-X-Y--Al-Cu--LAMMPS--ipr1)
Notes: To make the al-cu-set.txt file compatible with the eam/alloy style in LAMMPS, replace line 4 with "2 Al Cu" and the "D"s with "E"s in the numbers. This has been done in al-cu-set.eam.alloy.
File(s):
 
Citation: B. Jelinek, S. Groh, M.F. Horstemeyer, J. Houze, S.G. Kim, G.J. Wagner, A. Moitra, and M.I. Baskes (2012), "Modified embedded atom method potential for Al, Si, Mg, Cu, and Fe alloys", Physical Review B, 85(24), 245102. DOI: 10.1103/physrevb.85.245102.
Abstract: A set of modified embedded-atom method (MEAM) potentials for the interactions between Al, Si, Mg, Cu, and Fe was developed from a combination of each element's MEAM potential in order to study metal alloying. Previously published MEAM parameters of single elements have been improved for better agreement to the generalized stacking fault energy (GSFE) curves when compared with ab initio generated GSFE curves. The MEAM parameters for element pairs were constructed based on the structural and elastic properties of element pairs in the NaCl reference structure garnered from ab initio calculations, with adjustment to reproduce the ab initio heat of formation of the most stable binary compounds. The new MEAM potentials were validated by comparing the formation energies of defects, equilibrium volumes, elastic moduli, and heat of formation for several binary compounds with ab initio simulations and experiments. Single elements in their ground-state crystal structure were subjected to heating to test the potentials at elevated temperatures. An Al potential was modified to avoid formation of an unphysical solid structure at high temperatures. The thermal expansion coefficient of a compound with the composition of AA 6061 alloy was evaluated and compared with experimental values. MEAM potential tests performed in this work, utilizing the universal atomistic simulation environment (ASE), are distributed to facilitate reproducibility of the results.

LAMMPS pair_style meam (2012--Jelinek-B--Al-Si-Mg-Cu-Fe--LAMMPS--ipr2)
Notes: This file was sent by Bohumir Jelinek (Mississippi State University) and posted on 3 July 2012. He noted, "This is a MEAM potential for Al, Si, Mg, Cu, Fe alloys. It works with LAMMPS, version 19 Jul 2011 or later, when compiled with MEAM support. Most of the MEAM potential results presented in the accompanying paper can be reproduced with Atomistic Simulation Environment (ASE) and testing routines are provided in ase-atomistic-potential-tests-rev60.tar.gz"
File(s):
 
Citation: X.W. Zhou, D.K. Ward, and M.E. Foster (2018), "A bond-order potential for the Al–Cu–H ternary system", New Journal of Chemistry, 42(7), 5215-5228. DOI: 10.1039/c8nj00513c.
Abstract: Al-Based Al–Cu alloys have a very high strength to density ratio, and are therefore important materials for transportation systems including vehicles and aircrafts. These alloys also appear to have a high resistance to hydrogen embrittlement, and as a result, are being explored for hydrogen related applications. To enable fundamental studies of mechanical behavior of Al–Cu alloys under hydrogen environments, we have developed an Al–Cu–H bond-order potential according to the formalism implemented in the molecular dynamics code LAMMPS. Our potential not only fits well to properties of a variety of elemental and compound configurations (with coordination varying from 1 to 12) including small clusters, bulk lattices, defects, and surfaces, but also passes stringent molecular dynamics simulation tests that sample chaotic configurations. Careful studies verified that this Al–Cu–H potential predicts structural property trends close to experimental results and quantum-mechanical calculations; in addition, it properly captures Al–Cu, Al–H, and Cu–H phase diagrams and enables simulations of H2 dissociation, chemisorption, and absorption on Al–Cu surfaces.

LAMMPS pair_style bop (2018--Zhou-X-W--Al-Cu-H--LAMMPS--ipr1)
Notes: This file was sent by Dr. Xiaowang Zhou (Sandia National Laboratories) on September 9, 2018 and posted with his permission.
File(s):
 
Citation: X.W. Zhou, D.K. Ward, and M.E. Foster (2015), "An analytical bond-order potential for carbon", Journal of Computational Chemistry, 36(23), 1719-1735. DOI: 10.1002/jcc.23949.
Abstract: Carbon is the most widely studied material today because it exhibits special properties not seen in any other materials when in nano dimensions such as nanotube and graphene. Reduction of material defects created during synthesis has become critical to realize the full potential of carbon structures. Molecular dynamics (MD) simulations, in principle, allow defect formation mechanisms to be studied with high fidelity, and can, therefore, help guide experiments for defect reduction. Such MD simulations must satisfy a set of stringent requirements. First, they must employ an interatomic potential formalism that is transferable to a variety of carbon structures. Second, the potential needs to be appropriately parameterized to capture the property trends of important carbon structures, in particular, diamond, graphite, graphene, and nanotubes. Most importantly, the potential must predict the crystalline growth of the correct phases during direct MD simulations of synthesis to achieve a predictive simulation of defect formation. Because an unlimited number of structures not included in the potential parameterization are encountered, the literature carbon potentials are often not sufficient for growth simulations. We have developed an analytical bond order potential for carbon, and have made it available through the public MD simulation package LAMMPS. We demonstrate that our potential reasonably captures the property trends of important carbon phases. Stringent MD simulations convincingly show that our potential accounts not only for the crystalline growth of graphene, graphite, and carbon nanotubes but also for the transformation of graphite to diamond at high pressure.

Notes: Notes from Dr. Zhou about the C-Cu interactions: "The C-Cu potential was constructed from the carbon potential (2015--Zhou-X-W-Ward-D-K-Foster-M-E--C) and Cu of the Al-Cu and Cu-H potentials (2016--Zhou-X-W-Ward-D-K-Foster-M-E--Al-Cu, 2015--Zhou-X-W-Ward-D-K-Foster-M-Zimmerman-J-A--Cu-H), except that a Morse potential is added to the Cu so that the cohesive energy of Cu is deliberately significantly increased but the lattice constant of Cu is unchanged. This allows simulations of growth of C on Cu to be performed at temperatures higher than the Cu melting temperature (to accelerate the simulations) without other negative consequencies."

LAMMPS pair_style bop (2015--Zhou-X-W--C-Cu--LAMMPS--ipr1)
Notes: This file was taken from the August 22, 2018 LAMMPS distribution and listed as having been created by X.W. Zhou (Sandia)
File(s):
 
Citation: G. Bonny, R.C. Pasianot, N. Castin, and L. Malerba (2009), "Ternary Fe-Cu-Ni many-body potential to model reactor pressure vessel steels: First validation by simulated thermal annealing", Philosophical Magazine, 89(34-36), 3531-3546. DOI: 10.1080/14786430903299824.
Abstract: In recent years, the development of atomistic models dealing with microstructure evolution and subsequent mechanical property change in reactor pressure vessel steels has been recognised as an important complement to experiments. In this framework, a literature study has shown the necessity of many-body interatomic potentials for multi-component alloys. In this paper, we develop a ternary many-body Fe–Cu–Ni potential for this purpose. As a first validation, we used it to perform a simulated thermal annealing study of the Fe–Cu and Fe–Cu–Ni alloys. Good qualitative agreement with experiments is found, although fully quantitative comparison proved impossible, due to limitations in the used simulation techniques. These limitations are also briefly discussed.

Notes: Notes from Giovanni Bonny: The references for the elements and binary potentials used in Fe-Cu-Ni are
  • Fe: 'potential 2' from M.I. Mendelev, A. Han, D.J. Srolovitz, G.J. Ackland, D.Y. Sun and M. Asta, Phil. Mag. A 83 (2003) 3977.
  • Cu: 'EAM 1' from Y. Mishin, M.J. Mehl, D.A. Papaconstantopoulos, A.F. Voter, J.D. Kress, Phys. Rev. B 63 (2001) 224106.
  • Ni: A.F. Voter and S.P. Chen, Mater. Res. Soc. Symp. Proc. 82 (1987) 175.
  • FeCu: R.C. Pasianot and L. Malerba, J. Nucl. Mater. 360 (2007) 118.
  • FeNi: G. Bonny, R.C. Pasianot and L. Malerba, Model. Simul. Mater. Sci. Eng. 17 (2009) 025010.
F_Ni.spt was modified for densities past 4.8 because of a discontinuity. Unless for cascade conditions (for which the potential was not stiffened), the properties should stay exactly the same (equilibrium density is around 1).

LAMMPS pair_style eam/alloy (2009--Bonny-G--Fe-Cu-Ni--LAMMPS--ipr1)
Notes: This file was provided by Giovanni Bonny (Nuclear Materials Science Institute of SCK-CEN, Belgium) on 8 Feb. 2010.
File(s):
EAM tabulated functions
Notes: These files were provided by Giovanni Bonny on 8 Feb. 2010.
File(s):
Fe F(ρ): F_Fe.spt
Ni F(ρ): F_Ni.spt
Cu F(ρ): F_Cu.spt
Fe ρ(r): rhoFe.spt
Ni ρ(r): rhoNi.spt
Cu ρ(r): rhoCu.spt
Fe φ(r): pFeFe.spt
Ni φ(r): pNiNi.spt
Cu φ(r): pCuCu.spt
Fe-Ni φ(r): pFeNi.spt
Fe-Cu φ(r): pFeCu.spt
Cu-Ni φ(r): pCuNi.spt

 
Citation: X.W. Zhou, D.K. Ward, M. Foster, and J.A. Zimmerman (2015), "An analytical bond-order potential for the copper-hydrogen binary system", Journal of Materials Science, 50(7), 2859-2875. DOI: 10.1007/s10853-015-8848-9.
Abstract: Despite extensive studies in the past, deterioration of mechanical properties due to hydrogen environment exposure remains a serious problem for structural materials. More effective improvement of a material’s resilience requires advanced computational methods to elucidate the fundamental mechanisms of the hydrogen effects. To enable accurate molecular dynamics (MD) studies of the hydrogen effects on metals, we have developed a high-fidelity analytical bond-order potential (BOP) for the copper–hydrogen binary system as a representative case. This potential is available through the publically available MD code LAMMPS. The potential parameters are optimized using an iterative process. First, the potential is fitted to static and reactive properties of a variety of elemental and binary configurations including small clusters and bulk lattices (with coordination varying from 1 to 12). Then the potential is put through a series of rigorous MD simulation tests (e.g., vapor deposition and solidification) that involve chaotic initial configurations. It is demonstrated that this Cu–H BOP not only gives structural and property trends close to those seen in experiments and quantum mechanical calculations, but also predicts the correct phase transformations and chemical reactions in direct MD simulations. The correct structural evolution from chaotic initial states strongly verifies the transferability of the potential. A highly transferable potential is the reason that a well-parameterized analytical BOP can enable MD simulations of metal-hydrogen interactions to reach a fidelity level not achieved in the past.

LAMMPS pair_style bop (2015--Zhou-X-W--Cu-H--LAMMPS--ipr1)
Notes: This file was taken from the August 22, 2018 LAMMPS distribution and listed as having been created by X.W. Zhou (Sandia)
File(s):
 
Citation: B. Onat, and S. Durukanoğlu (2013), "An optimized interatomic potential for Cu–Ni alloys with the embedded-atom method", Journal of Physics: Condensed Matter, 26(3), 35404. DOI: 10.1088/0953-8984/26/3/035404.
Abstract: We have developed a semi-empirical and many-body type model potential using a modified charge density profile for Cu–Ni alloys based on the embedded-atom method (EAM) formalism with an improved optimization technique. The potential is determined by fitting to experimental and first-principles data for Cu, Ni and Cu–Ni binary compounds, such as lattice constants, cohesive energies, bulk modulus, elastic constants, diatomic bond lengths and bond energies. The generated potentials were tested by computing a variety of properties of pure elements and the alloy of Cu, Ni: the melting points, alloy mixing enthalpy, lattice specific heat, equilibrium lattice structures, vacancy formation and interstitial formation energies, and various diffusion barriers on the (100) and (111) surfaces of Cu and Ni.

LAMMPS pair_style eam/alloy (2013--Onat-B--Cu-Ni--LAMMPS--ipr1)
Notes: This file was taken from the August 22, 2018 LAMMPS distribution.
File(s): superseded


LAMMPS pair_style eam/alloy (2013--Onat-B--Cu-Ni--LAMMPS--ipr2)
Notes: This file was taken from openKIM model EAM_Dynamo_Onat_Durukanoglu_CuNi__MO_592013496703_004. It features more tabulation points and higher cutoffs for both rho and r.
File(s):
Citation: S.M. Foiles (1985), "Calculation of the surface segregation of Ni-Cu alloys with the use of the embedded-atom method", Physical Review B, 32(12), 7685-7693. DOI: 10.1103/physrevb.32.7685.
Abstract: The surface composition of Ni-Cu alloys has been calculated as a function of atomic layer, crystal face, and bulk composition at a temperature of 800 K. The results show that the composition varies nonmonotonically near the surface with the surface layer strongly enriched in Cu while the near-surface layers are enriched in Ni. The calculations use the embedded-atom method [M. S. Daw and M. I. Baskes, Phys. Rev. B 29, 6443 (1984)] in conjunction with Monte Carlo computer simulations. The embedding functions and pair interactions needed to describe Ni-Cu alloys are developed and applied to the calculation of bulk energies, lattice constants, and short-range order. The heats of segregation are computed for the dilute limit, and the composition profile is obtained for the (100), (110), and (111) surfaces for a variety of bulk compositions. The results are found to be in accord with experimental data.

LAMMPS pair_style eam (1985--Foiles-S-M--Ni-Cu--LAMMPS--ipr1)
Notes: These files were obtained from the December 9, 2007 LAMMPS distribution. According to Stephen M. Foiles, they differ from the original formulations in the following ways: a) The fcc is upper case in one and lower case in the other. b) The comment in the LAMMPS distribution for Ni_smf7.eam incorrectly lists it as being for the NiPd alloys rather than NiCu alloys. The potential file has been updated with "NiCu" to reflect the second comment.
File(s):
 
Citation: J.J. Hoyt, J.W. Garvin, E.B. Webb, and M. Asta (2003), "An embedded atom method interatomic potential for the Cu-Pb system", Modelling and Simulation in Materials Science and Engineering, 11(3), 287-299. DOI: 10.1088/0965-0393/11/3/302.
Abstract: A simple procedure is used to formulate a Cu–Pb pair interaction function within the embedded atom (EAM) method framework. Embedding, density and pair functions for pure Cu and pure Pb are taken from previously published EAM studies. Optimization of the Cu–Pb potential was achieved by comparing with experiment the computed heats of mixing for Cu–Pb liquid alloys and the equilibrium phase diagram, the latter being determined via a thermodynamic integration technique. The topology of the temperature-composition phase diagram computed with this EAM potential is consistent with experiment and features a liquid–liquid miscibility gap, low solubility of Pb in solid Cu and a monotectic reaction at approximately 1012 K.

LAMMPS pair_style eam/alloy (2003--Hoyt-J-J--Cu-Pb--LAMMPS--ipr1)
Notes: This file was supplied by J.J. Hoyt on 14 October 2008.
File(s):
 
Citation: G.P. Purja Pun, K.A. Darling, L.J. Kecskes, and Y. Mishin (2015), "Angular-dependent interatomic potential for the Cu-Ta system and its application to structural stability of nano-crystalline alloys", Acta Materialia, 100, 377-391. DOI: 10.1016/j.actamat.2015.08.052.
Abstract: Atomistic computer simulations are capable of providing insights into physical mechanisms responsible for the extraordinary structural stability and strength of immiscible Cu–Ta alloys. To enable reliable simulations of these alloys, we have developed an angular-dependent potential (ADP) for the Cu–Ta system by fitting to a large database of first-principles and experimental data. This, in turn, required the development of a new ADP potential for elemental Ta, which accurately reproduces a wide range of properties of Ta and is transferable to severely deformed states and diverse atomic environments. The new Cu–Ta potential is applied for studying the kinetics of grain growth in nano-crystalline Cu–Ta alloys with different chemical compositions. Ta atoms form nanometer-scale clusters preferentially located at grain boundaries (GBs) and triple junctions. These clusters pin some of the GBs in place and cause a drastic decrease in grain growth by the Zener pinning mechanism. The results of the simulations are well consistent with experimental observations and suggest possible mechanisms of the stabilization effect of Ta.

Notes: This potential is meant to supplant the Hahibon 2008 Cu-Ta ADP potential by providing a refit of the Ta-Ta and Cu-Ta interactions.

LAMMPS pair_style adp (2015--Purja-Pun-G-P--Cu-Ta--LAMMPS--ipr1)
Notes: This file was provided by Yuri Mishin (George Mason University) on 11 Sep. 2015.
File(s): superseded


LAMMPS pair_style adp (2015--Purja-Pun-G-P--Cu-Ta--LAMMPS--ipr2)
Notes: This file was provided by Yuri Mishin (George Mason University) on 2 Nov. 2018. Ganga Purja Pun noted that the tabulated values are identical to the version above except that the short range behaviors (r < 0.5 Angstroms) for some functions have been fixed so that they now follow the correct trends.
File(s):
Citation: A. Hashibon, A.Y. Lozovoi, Y. Mishin, C. Elsässer, and P. Gumbsch (2008), "Interatomic potential for the Cu-Ta system and its application to surface wetting and dewetting", Physical Review B, 77(9), 94131. DOI: 10.1103/physrevb.77.094131.
Abstract: An angle-dependent interatomic potential has been developed for the Cu-Ta system by crossing two existing potentials for pure Cu and Ta. The cross-interaction functions have been fitted to first-principles data generated in this work. The potential has been extensively tested against first-principles energies not included in the fitting database and applied to molecular dynamics simulations of wetting and dewetting of Cu on Ta. We find that a Cu film placed on a Ta (110) surface dewets from it, forming a Cu droplet on top of a stable Cu monolayer. We also observe that a drop of liquid Cu placed on a clean Ta (110) surface spreads over it as a stable monolayer, while the extra Cu atoms remain in the drop. The stability of a Cu monolayer and instability of thicker Cu films are consistent with recent experiments and first-principles calculations. This agreement demonstrates the utility of the potential for atomistic simulations of Cu-Ta interfaces.

Notes: Prof. Mishin requested the following be noted: There was a typing error in the original ADP paper (Y. Mishin, et al., Acta Mat. 53, 4029 (2005)). More information and a correction can be found in the FAQ. Update 17 Jan. 2014: Prof. Mishin noted that "Our ADP Ta potential has a known error: the elastic constants predicted by the potential as a factor of two different from those reported in the paper. This was the result of a bug in the fitting code that was used during the potential development. All other properties are exactly as reported in the paper. The mixed Cu-Ta interactions are also fine. However, because of this error in the elastic constants, the potential cannot be recommended for studying mechanical properties of pure Ta." Update: The 2015--Purja-Pun-G-P--Cu-Ta ADP potential has supplanted this potential.

ADP tabulated functions
Notes: These files were provided by Yuri Mishin (George Mason University) and posted on 22 Jan. 2010.
File(s): superseded


Citation: X.W. Zhou, R.A. Johnson, and H.N.G. Wadley (2004), "Misfit-energy-increasing dislocations in vapor-deposited CoFe/NiFe multilayers", Physical Review B, 69(14), 144113. DOI: 10.1103/physrevb.69.144113.
Abstract: Recent molecular dynamics simulations of the growth of [Ni0.8Fe0.2/Au] multilayers have revealed the formation of misfit-strain-reducing dislocation structures very similar to those observed experimentally. Here we report similar simulations showing the formation of edge dislocations near the interfaces of vapor-deposited (111) [NiFe/CoFe/Cu] multilayers. Unlike misfit dislocations that accommodate lattice mismatch, the dislocation structures observed here increase the mismatch strain energy. Stop-action observations of the dynamically evolving atomic structures indicate that during deposition on the (111) surface of a fcc lattice, adatoms may occupy either fcc sites or hcp sites. This results in the random formation of fcc and hcp domains, with dislocations at the domain boundaries. These dislocations enable atoms to undergo a shift from fcc to hcp sites, or vice versa. These shifts lead to missing atoms, and therefore a later deposited layer can have missing planes compared to a previously deposited layer. This dislocation formation mechanism can create tensile stress in fcc films. The probability that such dislocations are formed was found to quickly diminish under energetic deposition conditions.

FORTRAN
Notes: These are the original files sent by X.W. Zhou (Sandia National Laboratory) and posted with his permission. C.A. Becker (NIST) modified create.f to include the reference in the generated potential files and the EAM.input file for this composition. These files can be used to generate alloy potentials for Cu, Ag, Au, Ni, Pd, Pt, Al, Pb, Fe, Mo, Ta, W, Mg, Co, Ti, and Zr by editing EAM.input. However, as addressed in the reference, these potentials were not designed for use with metal compounds.
File(s): superseded


LAMMPS pair_style eam/alloy (2004--Zhou-X-W--Ta-Cu--LAMMPS--ipr1)
Notes: This file was generated by C.A. Becker (NIST) from create.f and posted with X.W. Zhou's (Sandia National Laboratory) permission. The tabulations in this file are identical to the tabulations in the "CuTa.eam.alloy" file in the August 22, 2018 LAMMPS distribution.
File(s): superseded


FORTRAN
Notes: The file Zhou04_create_v2.f is an updated version of create.f modified by L.M. Hale (NIST) following advice from X.W. Zhou (Sandia National Laboratory). This version removes spurious fluctuations in the tabulated functions of the original potential files caused by single/double precision floating point number conflicts.
File(s):
LAMMPS pair_style eam/alloy (2004--Zhou-X-W--Ta-Cu--LAMMPS--ipr2)
Notes: This file was generated by L.M. Hale from Zhou04_create_v2.f on 13 April 2018 and posted with X.W. Zhou's (Sandia National Laboratory) permission. This version corrects an issue with spurious fluctuations in the tabulated functions.
File(s):
 
Citation: V. Borovikov, M.I. Mendelev, and A.H. King (2016), "Effects of stable and unstable stacking fault energy on dislocation nucleation in nano-crystalline metals", Modelling and Simulation in Materials Science and Engineering, 24(8), 85017. DOI: 10.1088/0965-0393/24/8/085017.
Abstract: Dislocation nucleation from grain boundaries (GB) can control plastic deformation in nano-crystalline metals under certain conditions, but little is known about what controls dislocation nucleation, because when data from different materials are compared, the variations of many interacting properties tend to obscure the effects of any single property. In this study, we seek clarification by applying a unique capability of semi-empirical potentials in molecular dynamics simulations: the potentials can be modified such that all significant material properties but one, are kept constant. Using a set of potentials developed to isolate the effects of stacking fault energy, we show that for a given grain boundary, loading orientation and strain rate, the yield stress depends linearly on both the stable and unstable stacking fault energies. The coefficients of proportionality depend on the GB structure and the value of the yield stress is related to the density of the E structural units in the GB. While the impact of the stable stacking fault energy is easy to understand, the unstable stacking fault energy requires more elucidation and we provide a framework for understanding how it affects the nucleation and propagation process.

Notes: Dr. Mendelev noted that this potential was developed in the same manner as Cu-Zr_2.eam.fs, except that the original Cu potential was replaced by MCu31.eam.fs, which has more realistic stable and unstable stacking fault energies. This potential can be used to simulate the plastic deformation in the Cu-Zr amorphous alloys with embedded Cu particles.

LAMMPS pair_style eam/fs (2016--Borovikov-V--Cu-Zr--LAMMPS--ipr1)
Notes: These files were sent by M.I. Mendelev (Ames Laboratory) on 27 Sept. 2017 and posted with his permission.
File(s):
Citation: M.I. Mendelev, M.J. Kramer, R.T. Ott, D.J. Sordelet, D. Yagodin, and P. Popel (2009), "Development of suitable interatomic potentials for simulation of liquid and amorphous Cu-Zr alloys", Philosophical Magazine, 89(11), 967-987. DOI: 10.1080/14786430902832773.
Abstract: We present a new semi-empirical potential suitable for molecular dynamics simulations of liquid and amorphous Cu–Zr alloys. To provide input data for developing the potential, new experimental measurements of the structure factors for amorphous Cu64.5Zr35.5 alloy were performed. In this work, we propose a new method to include diffraction data in the potential development procedure, which also includes fitting to first-principles and liquid density and enthalpy of mixing data. To refine the new potential, we used first-principles and liquid enthalpy of mixing data published earlier combined with the densities of liquid Cu64.5Zr35.5 measured over a range of temperatures. We show that the potential predicts a liquid-to-glass transition temperature that agrees reasonably well with experimental data. Finally, we compare the new potential with two previously developed semi-empirical potentials for Cu–Zr alloys and examine their comparative and contrasting descriptions of structure and properties for Cu64.5Zr35.5 liquids and glasses.

LAMMPS pair_style eam/fs (2009--Mendelev-M-I--Cu-Zr--LAMMPS--ipr1)
Notes: This file was supplied by Mikhail Mendelev on 28 Nov. 2008. The reference was added on 22 Apr. 2009. Note added 14 Oct. 2010: the Cu part of this potential (M.I. Mendelev, et al., Phil. Mag. 88, 1723-1750 (2008)) has been posted separately on the Cu page to make it easier to use.
File(s):
Citation: M.I. Mendelev, D.J. Sordelet, and M.J. Kramer (2007), "Using atomistic computer simulations to analyze x-ray diffraction data from metallic glasses", Journal of Applied Physics, 102(4), 43501. DOI: 10.1063/1.2769157.
Abstract: We propose a method of using atomistic computer simulations to obtain partial pair correlation functions from wide angle diffraction experiments with metallic liquids and their glasses. In this method, a model is first created using a semiempirical interatomic potential and then an additional atomic force is added to improve the agreement with experimental diffraction data. To illustrate this approach, the structure of an amorphous Cu64.5Zr35.5 alloy is highlighted, where we present the results for the semiempirical many-body potential and fitting to x-ray diffraction data. While only x-ray diffraction data were used in the present work, the method can be easily adapted to the case when there are also data from neutron diffraction or even in combination. Moreover, this method can be employed in the case of multicomponent systems when the data of several diffraction experiments can be combined.

LAMMPS pair_style eam/fs (2007--Mendelev-M-I--Cu-Zr--LAMMPS--ipr1)
Notes: This file was supplied by Mikhail Mendelev. Note added 14 Oct. 2010: the Cu part of this potential (M.I. Mendelev, et al., Phil. Mag. 88, 1723-1750 (2008)) has been posted separately on the Cu page to make it easier to use. Except for comments, this file is equivalent to "CuZr_mm.eam.fs" in the August 22, 2018 LAMMPS distribution.
File(s):
Date Created: October 5, 2010 | Last updated: November 19, 2018