[gmx-users] force field for argon

[Dmitri Dubov]

Dear gmx'ers,

Inspecting gromacs' OPLSAA files, I find here two atom types for argon. File ffoplsaa.atp includes:
 opls_097   39.94800  ; Argon from Verlet & Weis     Mol.Phys.,24,1013 (1972) 
and
 Ar         39.948    ; Argon

LJ parameters are (file ffoplsaanb.itp):
[ atomtypes ]
; name  bond_type    mass    charge   ptype          sigma      epsilon
 opls_097   Ar  18   39.94800     0.000       A    3.40100e-01  9.78638e-01 ; SIG
...
 Ar         Ar     18	39.94800     0.000       A    3.41000e-01  2.74580e-02

The first set looks somewhat like the real Ar--Ar pair potential. 
A short comment before the second set says:
; These ion atomtypes are NOT part of OPLS, but since they are
; needed for some proteins or tutorial Argon simulations we have added them.

But its well depth is extremely low! What simulations is this set intended for?
-- 
Regards,
 Dmitri                          mailto:ddubov at ngs.ru
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