[gmx-users] Is there ff12sb equivalent of gbsa_ff99sb.itp?

[Richard Smith]

Hi gmx-users,

Is there ff12sb equivalent of gbsa_ff99sb.itp. Or an easy way to create 
one?

Objective:
To run an implicit solvent minimisation on 2yp7.pdb using the ff12sb 
force field.

Current Process is :
(1) Use amber12/bin/tleap to Amber inpcrd and prmtop files
(2) Use acpype to create GMX.gro and GMX.top files
(3) copy $PATH/gromacs/top/amber99sb.ff/gbsa.itp to current directory
(4) add "#include "./gbsa_ff99sb.itp" " to the .top file
(5) run a generic conjugate gradient minimisation. No ligands or ions 
are present

Running the same process ,but using the ff99sb force field the process 
runs.

With the ff12sb I get the below error message.

##
GB parameter(s) missing or negative for atom type 'CX'

GB parameter(s) missing or negative for atom type 'CO'

-------------------------------------------------------
Program grompp, VERSION 4.6.5


I understand adding parameters for CX and CO to the .itp file will 
eliminate this
problem.

I am just unable:
to establish if any significant GBSA parameters have changed between 
ff99 and ff12
and if not
  where I can find the appropriate Gromacs parameters that should be 
used for
'CO' and 'CX' atom types ( and any other atom types used in ff1sb and 
not in ff99sb).

Thanks.

-- 
-----------------------
Regards
Richard Smith

Research Associate
Department of Zoology
Centre for Pathogen Evoluton
University of Cambridge
Downing Street
Cambridge CB2 3EJ

Tel.: +44 (0)1223 330933