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2018--Mendelev-M-I-Zhang-F-Song-H-et-al--Tb

Citation: M.I. Mendelev, F. Zhang, H. Song, Y. Sun, C.Z. Wang, and K.M. Ho (2018), "Molecular dynamics simulation of the solid-liquid interface migration in terbium", The Journal of Chemical Physics, 148(21), 214705. DOI: 10.1063/1.5026922.
Abstract: We developed a Tb embedded atom method potential which properly reproduces the liquid structure obtained from the ab initio molecular dynamics simulation, the hexagonal close packed (hcp)-body-centered cubic (bcc) phase transformation, and melting temperatures. At least three crystal phases [hcp, face-centered cubic (fcc), and bcc] described by this potential can coexist with the liquid phase. Thus, the developed potential provides an excellent test bed for studies of the completive phase nucleation and growth in a single component system. The molecular dynamics simulation showed that all crystal phases can grow from the liquid phase close to their melting temperatures. However, in the cases of the hcp and fcc growth from the liquid phase at very large supercoolings, the bcc phase forms at the solid-liquid interface in the close packed orientations in spite of the fact that both hcp and fcc phases are more stable than the bcc phase at these temperatures. This bcc phase closes the hcp and fcc phase from the liquid such that the remaining liquid solidifies into the bcc phase. The initial hcp phase then slowly continues growing in expense of the bcc phase.

Notes: Dr. Mendelev noted that this potential was developed to simulate the solidification and hcp-bcc transformation. Update 2018-08-19: Reference information updated.

LAMMPS pair_style eam/fs (2018--Mendelev-M-I--Tb--LAMMPS--ipr1)
See Computed Properties
Notes: This file was sent by M.I. Mendelev (Ames Laboratory) on 12 Feb. 2018 and posted with his permission.
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Implementation Information

This page displays computed properties for the 2018--Mendelev-M-I--Tb--LAMMPS--ipr1 implementation of the 2018--Mendelev-M-I-Zhang-F-Song-H-et-al--Tb potential. Computed values for other implementations can be seen by clicking on the links below:

Cohesive Energy vs. Interatomic Spacing

Plots of the cohesive energy vs interatomic spacing, r, are shown below for a number of crystal structures. The values were computed using the iprPy E_vs_r_scan calculation method. The structures are generated based on the ideal atomic positions and b/a and c/a lattice parameter ratios for a given crystal prototype. The size of the system is then uniformly scaled, and the energy calculated without relaxing the system. To obtain these plots, values of r are evaluated every 0.02 Å up to 6 Å. Clicking on the image of a plot will open an interactive version of it in a new tab. The underlying data for the plots can be downloaded by clicking on the links above each plot.

Notes and Disclaimers:

  • These values are meant to be guidelines for comparing potentials, not the absolute values for any potential's properties. Values listed here may change if the calculation methods are updated due to improvements/corrections. Variations in the values may occur for variations in calculation methods, simulation software and implementations of the interatomic potentials.
  • The minima identified by this calculation do not guarantee that the associated crystal structures will be stable since no relaxation is performed.
  • NIST disclaimer

Version Information:

  • 2019-02-04. Values regenerated with even r spacings of 0.02 Å, and now include values less than 2 Å when possible. Updated calculation method and parameters enhance compatibility with more potential styles.
  • 2019-04-26. Results for hcp, double hcp, α-As and L10 prototypes regenerated from different unit cell representations. Only α-As results show noticable (>1e-5 eV) difference due to using a different coordinate for Wykoff site c position.
  • 2018-06-13. Values for MEAM potentials corrected. Dynamic versions of the plots moved to separate pages to improve page loading. Cosmetic changes to how data is shown and updates to the documentation.
  • 2017-01-11. Replaced png pictures with interactive Bokeh plots. Data regenerated with 200 values of r instead of 300.
  • 2016-09-28. Plots for binary structures added. Data and plots for elemental structures regenerated. Data values match the values of the previous version. Data table formatting slightly changed to increase precision and ensure spaces between large values. Composition added to plot title and structure names made longer.
  • 2016-04-07. Plots for elemental structures added.

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Click on plot to load interactive version

2018--Mendelev-M-I--Tb--LAMMPS--ipr1/EvsR.Tb

Crystal Structure Predictions

Computed lattice constants and cohesive energies are displayed for a variety of crystal structures. The values displayed here are obtained using the following process.

  1. Initial crystal structure guesses are taken from:
    1. The iprPy E_vs_r_scan calculation results (shown above) by identifying all energy minima along the measured curves for a given crystal prototype + composition.
    2. Structures in the Materials Project and OQMD DFT databases.
  2. All initial guesses are relaxed using three independent methods using a 10x10x10 supercell:
    1. "box": The system's lattice constants are adjusted to zero pressure without internal relaxations using the iprPy relax_box calculation with a strainrange of 1e-6.
    2. "static": The system's lattice and atomic positions are statically relaxed using the iprPy relax_static calculation with a minimization force tolerance of 1e-10 eV/Angstrom.
    3. "dynamic": The system's lattice and atomic positions are dynamically relaxed for 10000 timesteps of 0.01 ps using the iprPy relax_dynamic calculation with an nph integration plus Langevin thermostat. The final configuration is then used as input in running an iprPy relax_static calculation with a minimization force tolerance of 1e-10 eV/Angstrom.
  3. The relaxed structures obtained from #2 are then passed as inputs to the iprPy crystal_space_group calculation. This calculation uses the spglib package to identify an ideal crystal unit cell based on the results.
  4. The space group information of the ideal unit cells is compared to the space group information of the corresponding reference structures to identify which structures transformed upon relaxation. The structures that did not transform to a different structure are listed in the table(s) below. The "method" field indicates the most rigorous relaxation method where the structure did not transform. The space group information is also used to match the DFT reference structures to the used prototype, where possible.

Notes and Disclaimers:

  • These values are meant to be guidelines for comparing potentials, not the absolute values for any potential's properties. Values listed here may change if the calculation methods are updated due to improvements/corrections. Variations in the values may occur for variations in calculation methods, simulation software and implementations of the interatomic potentials.
  • The presence of any structures in this list does not guarantee that those structures are stable. Also, the lowest energy structure may not be included in this list.
  • Multiple values for the same crystal structure but different lattice constants are possible. This is because multiple energy minima are possible for a given structure and interatomic potential. Having multiple energy minima for a structure does not necessarily make the potential "bad" as unwanted configurations may be unstable or correspond to conditions that may not be relevant to the problem of interest (eg. very high strains).
  • NIST disclaimer

Version Information:

  • 2019-06-07. Structures with positive or near zero cohesive energies removed from the display tables. All values still present in the raw data files.
  • 2019-04-26. Calculations now computed for each implementation. Results for hcp, double hcp, α-As and L10 prototypes regenerated from different unit cell representations.
  • 2018-06-14. Methodology completely changed affecting how the information is displayed. Calculations involving MEAM potentials corrected.
  • 2016-09-28. Values for simple compounds added. All identified energy minima for each structure are listed. The existing elemental data was regenerated. Most values are consistent with before, but some differences have been noted. Specifically, variations are seen with some values for potentials where the elastic constants don't vary smoothly near the equilibrium state. Additionally, the inclusion of some high-energy structures has changed based on new criteria for identifying when structures have relaxed to another structure.
  • 2016-04-07. Values for elemental crystal structures added. Only values for the global energy minimum of each unique structure given.

Select a composition:

Download raw data (including filtered results)

Reference structure matches:
A1--Cu--fcc = mp-7163, oqmd-1215733, oqmd-9301
A15--beta-W = oqmd-1215020
A2--W--bcc = mp-11446, oqmd-17350
A3'--alpha-La--double-hcp = oqmd-1215466
A3--Mg--hcp = mp-18, oqmd-17349
A4--C--dc = oqmd-1215555
A5--beta-Sn = oqmd-1215644

prototypemethodEcoh (eV)a0 (Å)b0 (Å)c0 (Å)α (degrees)β (degrees)γ (degrees)
A3--Mg--hcpdynamic-4.19093.6253.6255.65890.090.0120.0
oqmd-1215287box-4.18943.59276.33435.658490.090.090.0
mp-11698dynamic-4.18523.62913.629125.937690.090.0120.0
A1--Cu--fccdynamic-4.18495.16235.16235.162390.090.090.0
mp-571249dynamic-4.18363.64693.646917.659890.090.0120.0
A3'--alpha-La--double-hcpdynamic-4.1833.64053.640511.676990.090.0120.0
A2--W--bccdynamic-4.17433.94833.94833.948390.090.090.0
oqmd-1214931dynamic-4.09768.74688.74688.746890.090.090.0
oqmd-1214931box-4.09518.72588.72588.725890.090.090.0
oqmd-1214842dynamic-4.069412.303712.303712.303790.090.090.0
A15--beta-Wdynamic-4.06826.54586.54586.545890.090.090.0
oqmd-1214842box-4.049512.42312.42312.42390.090.090.0
oqmd-1215109box-3.94675.633412.12193.756590.090.090.0
oqmd-1214753box-3.94455.642212.11673.751890.090.090.0
A5--beta-Snstatic-3.80446.13986.13983.291590.090.090.0
Ah--alpha-Po--scstatic-3.52963.35853.35853.358590.090.090.0
A4--C--dcstatic-2.82637.3197.3197.31990.090.090.0
Date Created: October 5, 2010 | Last updated: June 07, 2019