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Citation: S. Han, L.A. Zepeda-Ruiz, G.J. Ackland, R. Car, and D.J. Srolovitz (2003), "Interatomic potential for vanadium suitable for radiation damage simulations", Journal of Applied Physics, 93(6), 3328-3335. DOI: 10.1063/1.1555275.
Abstract: The ability to predict the behavior of point defects in metals, particularly interstitial defects, is central to accurate modeling of the microstructural evolution in environments with high radiation fluxes. Existing interatomic potentials of embedded atom method type predict disparate stable interstitial defect configurations in vanadium. This is not surprising since accurate first-principles interstitial data were not available when these potentials were fitted. In order to provide the input information required to fit a vanadium potential appropriate for radiation damage studies, we perform a series of first-principles calculations on six different interstitial geometries and vacancies. These calculations identify the 〈111〉 dumbbell as the most stable interstitial with a formation energy of approximately 3.1 eV, at variance with predictions based upon existing potentials. Our potential is of Finnis–Sinclair type and is fitted exactly to the experimental equilibrium lattice parameter, cohesive energy, elastic constants and a calculated unrelaxed vacancy formation energy. Two additional potential parameters were used to obtain the best fit to the set of interstitial formation energies determined from the first-principles calculations. The resulting potential was found to accurately predict both the magnitude and ordering of the formation energies of six interstitial configurations and the unrelaxed vacancy ground state, in addition to accurately describing the migration characteristics of the stable interstitial and vacancy. This vanadium potential is capable of describing the point defect properties appropriate for radiation damage simulations as well as for simulations of more common crystal and simple defect properties.

Moldy FS
Notes: The parameters in V.moldy were obtained from http://homepages.ed.ac.uk/graeme/moldy/moldy.html and posted with the permission of G.J. Ackland.
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LAMMPS pair_style eam/fs (2003--Han-S--V--LAMMPS--ipr1)
Notes: A conversion to LAMMPS from MOLDY was performed by G.J. Ackland and submitted on 10 Oct. 2017.
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Citation: G.J. Ackland, and R. Thetford (1987), "An improved N-body semi-empirical model for body-centred cubic transition metals", Philosophical Magazine A, 56(1), 15-30. DOI: 10.1080/01418618708204464.
Abstract: The recently published semi-empirical potentials of Finnis and Sinclair for the metals V, Nb, Ta, Mo and W appear to give unphysical results for properties involving small interatomic separation. This is remedied by adding to the potentials cores fitted to electron gas calculations on dimers. The adjusted potentials are shown to predict a more realistic pressure-volume relationship. Interstitial formation energies are calculated for various configurations, using quenched molecular dynamics and static relaxation. Some preliminary results on interstitial migration are presented.

Equations
Notes: The file AckThet.pdf was obtained from http://homepages.ed.ac.uk/graeme/moldy/moldy.html and posted with the permission of G.J. Ackland.
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Citation: M.I. Mendelev, S. Han, W.- Son, G.J. Ackland, and D.J. Srolovitz (2007), "Simulation of the interaction between Fe impurities and point defects in V", Physical Review B, 76(21), 214105. DOI: 10.1103/physrevb.76.214105.
Abstract: We report improved results of atomistic modeling of V-Fe alloys. We introduced an electronic structure embedding approach to improve the description of the point defects in first-principles calculations, by including the semicore electrons in some V atoms (those near the interstitial where the semicore levels are broadened) but not those further from the point defect. This enables us to combine good accuracy for the defect within large supercells and to expand the data set of first-principles point defect calculations in vanadium with and without small amounts of iron. Based on these data, previous first-principles work, and new calculations on the alloy liquid, we fitted an interatomic potential for the V-Fe system which describes the important configurations likely to arise when such alloys are exposed to radiation. This potential is in a form suitable for molecular dynamics (MD) simulations of large systems. Using the potential, we have calculated the migration barriers of vacancies in the presence of iron, showing that these are broadly similar. On the other hand, MD simulations show that V self-diffusion at high temperatures and Fe diffusion are greatly enhanced by the presence of interstitials.

LAMMPS pair_style eam/fs (2007--Mendelev-M-I--V-Fe--LAMMPS--ipr1)
Notes: This file was provided by Mikhail Mendelev. Except for comments, this file is equivalent to "VFe_mm.eam.fs" in the August 22, 2018 LAMMPS distribution.
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Citation: S.B. Maisel, W.-S. Ko, J.-L. Zhang, B. Grabowski, and J. Neugebauer (2017), "Thermomechanical response of NiTi shape-memory nanoprecipitates in TiV alloys", Physical Review Materials, 1(3), 33610. DOI: 10.1103/physrevmaterials.1.033610.
Abstract: We study the properties of NiTi shape-memory nanoparticles coherently embedded in TiV matrices using three-dimensional atomistic simulations based on the modified embedded-atom method. To this end, we develop and present a suitable NiTiV potential for our simulations. Employing this potential, we identify the conditions under which the martensitic phase transformation of such a nanoparticle is triggered—specifically, how these conditions can be tuned by modifying the size of the particle, the composition of the surrounding matrix, or the temperature and strain state of the system. Using these insights, we establish how the transformation temperature of such particles can be influenced and discuss the practical implications in the context of shape-memory strengthened alloys.

LAMMPS pair_style meam (2017--Maisel-S-B--V-Ni-Ti--LAMMPS--ipr1)
Notes: These files were sent by Won-Seok Ko (School of Materials Science and Engineering, University of Ulsan) on 9 Feb. 2018 and posted with his permission.
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Date Created: October 5, 2010 | Last updated: October 05, 2018