Is the interatomic potential values tabulated in DYNAMO setfl format r*phi or just only phi?

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1

Dear all,

I’m confused by the description of the pair_eam document and the source code to generate eam potential in the tools/eam_generate in lammps source tree.

The pair_eam document here said:

Unlike the effective charge array Z® in funcfl files, the tabulated values for each phi function are listed in setfl files directly as r*phi (in units of eV-Angstroms), since they are for atom pairs.

For me, my comprehension is that the phi function listed in setfl is the value of r*phi.

However, the source code of Cu_Mishin1.eam in the tools folder shows this:

double V (double r) {
return ( E1M(r,r01,a1) + E2M(r,r02,a2) + d ) * psi ( (r-rc)/h ) -
H (rs1-r)S1pow(rs1-r, 4.) -
H (rs2-r)S2pow(rs2-r, 4.) -
H (rs3-r)S3pow(rs3-r, 4.);
}

// Pair potential
for (i = 0; i < Nr; i++)
fprintf (LAMMPSFile, “%20.20f\n”, V ((double)idr) * (double)idr);

The function V is the same as the interatomic potential function published on Phys. Rev. B 63, 224106 (2001), but I cannot figure out what does the multiplication mean in the “fprintf” part, if it is rphi, it should be written as V((double)idr)(idr) instead.

In summary, at least for the EAMs in the tools folder of LAMMPS, how is the interatomic potential function (phi) exactly expressed?

Thanks,

Jason

2

I don’t know anything about the EAM styles, but isn’t your expression equivalent with the source code? The integer i is cast to double both in the argument of V and again when V® is multiplied by i*dr, so it reads V®*r, which is also what your expression would give you.

3

Within the LAMMPS potentials dir, files ending
in *.eam are funcfl (single-element files). Files
ending in *.eam.alloy are setfl files. So if the
tool is generating a *.eam file, its not a setfl file.

Steve