[gmx-users] mdp options for charmm27 force field in gromacs version 4.6.7

[Christopher Neale]

Dear Users:

I would like to use the charmm27 force field in gromacs version 4.6.7 and I would like to know if it is possible to get the proper treatment of vdw interactions.

Information for gromacs 5 is here:
http://www.gromacs.org/Documentation/Terminology/Force_Fields/CHARMM

However, Gromacs 4.6.7 does not contain the option for vdw-modifier = force-switch

  Invalid enum 'force-switch' for variable vdw-modifier, using
  'Potential-shift-Verlet'
  Next time use one of: 'Potential-shift-Verlet' 'Potential-shift' 'None'
  'Potential-switch' 'Exact-cutoff'

Is a potential-shift the same as a force-switch and therefore the following options are correct for charmm27 in gromacs 4.6.7?

ns_type = grid
cutoff-scheme = verlet
vdwtype = cut-off
rlist = 1.2
rvdw = 1.2
rvdw-switch = 1.0
rcoulomb = 1.2
vdw-modifier = Potential-shift-Verlet
coulombtype = PME

I know this has been discussed before on the list, but I can't find anything that seems authoritative for gromacs versions prior to v5.

Thank you for your assistance,
Chris.