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Thursday, April 16, 2015

GOLD potentials for molecular dynamics and melting point

Gold (Au)

In the standard package of LAMMPS, the potential of Au is (Foiles,1986; S.M. Foiles, M.I. Baskes, and M.S. Daw, Phys. Rev. B 33, 7983, 1986).

Hoyt,2002 (Atomistic computation of liquid diffusivity, solid-liquid interfacial free
energy and kinetic coefficient in Au and Ag, J. J. Hoyt, M.Asta, Phys

Rev B, 65, 214106 (2002)
In recent MD studies of the solid-liquid interfacial free energy in Ni the sensitivity of the calculated values of gamma (g) to the details of the EAM potential were investigated. It was concluded that the calculated value of g depends on the accuracy of the melting point predicted by the interatomic potential
and the value of the anisotropy varied somewhat depending on the specific choice of the EAM potential. Those potentials which more accurately reproduced the elastic properties of the crystal yielded anisotropies in close agreement.
In the present work the embedded atom potentials formulated
by (Voter and Chen, 1978; A.F. Voter and S.P. Chen, in Characterization of Defects in Materials,
edited by R. W. Siegel and R. Sinclair, MRS Symposia Proceedings No. 82; Materials Research Society, Pittsburgh, 1978, p. 175. ) have been employed throughout. The Voter-Chen potentials are superior to the
earlier versions due to Foiles, Baskes, and Daw (S.M. Foiles, M.I. Baskes, and M.S. Daw, Phys. Rev. B 33, 7983, 1986)  in terms of the predicted elastic properties of the solid phase. The melting point of Au for the VC potential is closer to experiment than the FBD version whereas the melting point for Ag is slightly worse. 
The melting point for the EAM potentials can be found by monitoring the solid-liquid interface velocity vs temperature and extrapolating to the temperature corresponding to zero motion. With this procedure we find the melting point for Ag to be 1115 K and 1120 K for Au. These values are below the actual measured melting points of 1234 K and 1338 K for Ag and Au, respectively, but the agreement with experiment is
reasonable given that no properties of the liquid were utilized in the potential fit procedure. For comparison, the melting points for the Foiles, Baskes, and Daw EAM potentials are 1170 for Ag and 1090 for Au. 


G. Grochola, S.P. Russo, and I.K. Snook, "On fitting a gold embedded atom method potential using the force matching method," J. Chem. Phys., 123, 204719 (2005). DOI: 10.1063/1.2124667. 

Notes: This file was generated by C.A. Becker from the files below that were approved by G. Grochola (RMIT University) and posted with his permission on 21 Feb. 2011. This version is compatible with LAMMPS. Validation and usage information can be found in Au-Grochola-JCP05-conversion-notes_v2.pdf. If you use this eam.alloy file, please credit the website in addition to the original reference. 

Format: EAM/alloy setfl 
File(s): Au-Grochola-JCP05.eam.alloy 

Notes: These files were approved by G. Grochola. 

Format: EAM table 
F(ρ): Au-Grochola-JCP05-F.table 
ρ(r): Au-Grochola-JCP05-rou.table 
φ(r): Au-Grochola-JCP05-Phi.table 

X.W. Zhou, R.A. Johnson, and H.N.G. Wadley, "Misfit-energy-increasing dislocations in vapor-deposited CoFe/NiFe multilayers," Phys. Rev. B,69, 144113 (2004). DOI: 10.1103/PhysRevB.69.144113. 

Notes: This file was generated by C.A. Becker from the files sent by X.W. Zhou (Sandia National Laboratory) and posted with his permission. 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. See the Zhou04 page for more information. 

Format: EAM/alloy setfl 
File(s): Au.set 

J.B. Adams, S.M. Foiles, and W.G. Wolfer, "Self-diffusion and impurity diffusion of FCC metals using the 5-frequency model and the Embedded Atom Method," J. Mater. Res. 4, 102-112 (1989). 

Notes: auu6.txt was obtained from 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.' This file is compatible with the "pair_style eam" format in LAMMPS (19Feb09 version). 

Format: EAM 
File(s): auu6.txt 

G.J. Ackland, G.I. Tichy, V. Vitek, and M.W. Finnis, "Simple N-body potentials for the noble-metals and nickel," Phil. Mag. A 56, 735-756 (1987). 

Notes: The parameters in au.moldy were obtained from and posted with the permission of G.J. Ackland. 

Format: Moldy FS 
File(s): au.moldy 

Notes: This conversion was performed from G.J. Ackland's parameters by M.I. Mendelev. Conversion checks from M.I. Mendelev can be found inconversion_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. 

Format: EAM/FS setfl 
File(s): Au.eam.fs 


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