lammps/potentials/SiCGe.tersoff

# Tersoff parameters for various elements and mixtures
# multiple entries can be added to this file, LAMMPS reads the ones it needs
# these entries are in LAMMPS "metal" units:
#   A,B = eV; lambda1,lambda2,lambda3 = 1/Angstroms; R,D = Angstroms
#   other quantities are unitless

# Aidan Thompson (athomps at sandia.gov) takes full blame for this
# file.  It specifies various potentials published by J. Tersoff for
# silicon, carbon and germanium. Since Tersoff published several
# different silicon potentials, I refer to them using atom types
# Si(B), Si(C) and Si(D). The last two are almost almost identical but
# refer to two different publications. These names should be used in
# the LAMMPS command when the file is invoked. For example:
# pair_coeff * * SiCGe.tersoff Si(B).  The Si(D), C and Ge potentials
# can be used pure silicon, pure carbon, pure germanium, binary SiC,
# and binary SiGe, but not binary GeC or ternary SiGeC. LAMMPS will
# generate an error if this file is used with any combination
# involving C and Ge, since there are no entries for the GeC
# interactions (Tersoff did not publish parameters for this
# cross-interaction.)

# format of a single entry (one or more lines):
#   element 1, element 2, element 3, 
#   m, gamma, lambda3, c, d, costheta0, n, beta, lambda2, B, R, D, lambda1, A

# The original Tersoff potential for Silicon, Si(B)
# J. Tersoff, PRB, 37, 6991 (1988) 

Si(B)  Si(B)   Si(B)  3.0 1.0 1.3258 4.8381 2.0417 0.0000 22.956
             0.33675  1.3258  95.373  3.0  0.2  3.2394  3264.7

# The later Tersoff potential for Silicon, Si(C)
# J. Tersoff, PRB, 38, 9902 (1988) 

Si(C)  Si(C)   Si(C)  3.0 1.0 1.7322 1.0039e5 16.218 -0.59826 0.78734
             1.0999e-6  1.7322  471.18  2.85  0.15  2.4799  1830.8

# The later Tersoff potential for Carbon, Silicon, and Germanium
# J. Tersoff, PRB, 39, 5566 (1989) + errata (PRB 41, 3248)
# The Si and C parameters are very close to those in SiC.tersoff

C      C       C         3.0 1.0 0.0 3.8049e4 4.3484 -0.57058 0.72751 1.5724e-7  2.2119  346.74    1.95    0.15   3.4879  1393.6
Si(D)  Si(D)   Si(D)     3.0 1.0 0.0 1.0039e5 16.217 -0.59825 0.78734 1.1000e-6  1.7322  471.18    2.85    0.15   2.4799  1830.8
Ge     Ge      Ge        3.0 1.0 0.0 1.0643e5 15.652 -0.43884 0.75627 9.0166e-7  1.7047  419.23    2.95    0.15   2.4451  1769.0

C      Si(D)   Si(D)     3.0 1.0 0.0 3.8049e4 4.3484 -0.57058 0.72751 1.5724e-7  1.97205 395.1451  2.3573  0.1527 2.9839  1597.3111
C      Si(D)   C         3.0 1.0 0.0 3.8049e4 4.3484 -0.57058 0.72751 0.0        0.0     0.0       1.95    0.15   0.0     0.0
C      C       Si(D)     3.0 1.0 0.0 3.8049e4 4.3484 -0.57058 0.72751 0.0        0.0     0.0       2.3573  0.1527 0.0     0.0

Si(D)  C       C         3.0 1.0 0.0 1.0039e5 16.217 -0.59825 0.78734 1.1000e-6  1.97205 395.1451  2.3573  0.1527 2.9839  1597.3111
Si(D)  Si(D)   C         3.0 1.0 0.0 1.0039e5 16.217 -0.59825 0.78734 0.0        0.0     0.0       2.3573  0.1527 0.0     0.0
Si(D)  C       Si(D)     3.0 1.0 0.0 1.0039e5 16.217 -0.59825 0.78734 0.0        0.0     0.0       2.85    0.15   0.0     0.0
 
Si(D)  Ge      Ge        3.0 1.0 0.0 1.0039e5 16.217 -0.59825 0.78734 1.1000e-6  1.71845 444.7177  2.8996  0.1500 2.4625  1799.6347
Si(D)  Si(D)   Ge        3.0 1.0 0.0 1.0039e5 16.217 -0.59825 0.78734 0.0        0.0     0.0       2.8996  0.1500 0.0     0.0
Si(D)  Ge      Si(D)     3.0 1.0 0.0 1.0039e5 16.217 -0.59825 0.78734 0.0        0.0     0.0       2.85    0.15   0.0     0.0
 
Ge     Si(D)   Si(D)     3.0 1.0 0.0 1.0643e5 15.652 -0.43884 0.75627 9.0166e-7  1.71845 444.7177  2.8996  0.1500 2.4625  1799.6347
Ge     Si(D)   Ge        3.0 1.0 0.0 1.0643e5 15.652 -0.43884 0.75627 0.0        0.0     0.0       2.95    0.15   0.0     0.0
Ge     Ge      Si(D)     3.0 1.0 0.0 1.0643e5 15.652 -0.43884 0.75627 0.0        0.0     0.0       2.8996  0.1500 0.0     0.0