[gmx-users] oplsaa force field

[Dongsheng Zhang]

Dear GMX users,

In ffoplsaanb.itp, there are 8 columns.
; name  bond_type    mass    charge   ptype          sigma      epsilon
 opls_001   C	6      12.01100     0.500       A    3.75000e-01
4.39320e-01 ; SIG

In ffG53a5nb.itp, there are 7 columns.
[ atomtypes ]
;name  at.num   mass      charge ptype       c6           c12
    O    8 	0.000      0.000     A  0.0022619536       1e-06

Could anyone tell me how gromacs knows to read 8 columns for oplsaa FF,
but 7 columns for gromos FF? Thanks!



Have a nice weekend!



Dongsheng