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[lammps-users] lj parameters
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[lammps-users] lj parameters

From: Hossein Geraili <geraili.hsn@...24...>
Date: Tue, 12 Sep 2017 22:36:21 +0430

Dear Lammps users,

I am using force field parameters of my molecule from an article which is using this formula for pair interaction potential:
{eps ij [(rmin ij/r ij)^12 -(rmin ij/r ij)^6] + q i q j/r ij}
but I know the correct formula for rmin is( a 2 is missing):
eps ij [(rmin ij/r ij)^12 - 2*(rmin ij/r ij)^6].
anyway, I should use pair_style lj/cut/coul/long for my system, which the VdW part is:
4*eps ij [(sig. ij/r ij)^12 - (sig. ij/r ij)^6].
and I know the relation between sig. and rmin:
rmin ij = (2)^1/6 *sig. ij
I wanted to ask, should I convert these to lammps, like converting rmin  to sig. and considering the changes( like 2, 4) and take them into account at inputting sig. and eps. values? or it is not necessary and lammps would consider rmin as sig.?
excuse me if it is obvious, but I cannot be sure which one is correct.
thanks in advance.

Hosein Geraili Daronkola
M.Sc.Graduated of physical chemistry
Physical Chemistry,
Department of Chemistry,
Sharif University of Technology.

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