Dear everyone,
I need to slightly modify the Au_u3.eam potential file which is in the potential folder of LAMMPS package. But I am confused about three problems.
(1) According to the original paper Foiles etc., PRB 33 (1986) 7983, for pure Au materials, the effective charge is expressed as Z(r) =11*(1+0.1269*r*r)*exp(-1.4475*r), and the pair repulsion potential is given by phi(r)=Z(r)*Z(r)/r. But according to the doc page of pair_style eam command in LAMMPS manual, it says that pair potential term is calculated via the formula r*phi=27.2 * 0.529 * Zi * Zj, i.e. phi(r)=27.2*0.529*79*79/r for pure Au. Can anybody please tell me that whether these two methods are consistent with each other in calculating phi and why is that?
(2) The effective charge is listed from line 104 to line 203 in Au_u3.eam, the interval of distance r is 1.1212121212121229e-02 angstrom which is also given in the file. If I want to plot a figure of the distance r vs. effective charge Z(r), distance r should start at 0 angstrom or at 1.1212121212121229e-02 angstrom? i.e., r=0, dr, 2*dr, ……, 499*dr or r=dr,2*dr,3*dr, ……, 500*dr. Could you please tell me which one is correct?
(3) I thought Nr*dr should equal cutoff before. But here in Au_u3.eam, it does not, which obviously can be seen from that 500*1.1212121212121229e-02 not equal 5.5500000000000114e+00. Could you tell me why?
Any help would be much appreciated!
With My Best Regards
Wenqiang Liu
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