Dear lammps users,
I am trying to calculate the interatomic energy between two Au particles as a function of separation distance by hand using the Auu3.eam potential file developed by Foiles and the equation in pair_style eam page. According to lammps documentation, the 1st, 2nd and 3rd 500 values in Auu3.eam corresponds to the embedding function F(rho), the effective charge function Z(r), and the density function rho(r), respectively. And for the calculation of pairwise repulsion at r = 0,dr,2*dr, … (Nr1)*dr, I used:
phi = (27.2 * 0.529 * Z^2) / r as the system only involves gold atoms.
For the embedding energy I just took directly the 1st 500 values.
However, my results are incorrect as the total energy does not approach to zero at large separation distances. Following are some comments regarding my calculation:

F(rho) is a function of rho(r), however, both values are provided in Auu3.eam, I’m not sure why the rho(r) values are needed when we already have F(rho) and I didn’t use rho(r) in my calculations.

I calculated the interatomic energy at r = 0,dr,2*dr, … (Nr1)*dr and took the F(rho) and Z(r) values at each separation, I’m not sure if this is the right way.

The interatomic energy is pairwise energy as only two atoms are involved. In this case, the manybody effect is neglected, is this correct?
The Auu3.eam potential file is attached as follows:
(https://www.ctcms.nist.gov/potentials/Download/1986FoilesSMBaskesMIDawMSAu/1/Au_u3.eam)
I really appreciate any help provided and will be of great pleasure to hear from you.
Kind regards,
Shaelyn