[gmx-users] Help with the heme group in forcefield gromos53a6

[Tanos Franca]

Dear users,
We are trying to perform a MD simulation of a protein with a heme group 
using the
gromos53a6 force field but, when trying to run grompp, we receive the 
error mesage:
Program grompp, VERSION 4.0.3
Source code file: ../../../../src/kernel/toppush.c, line: 947

Fatal error:
Atomtype FE2+ not found

How can it happen if the gromos53a6 force field have parameters to the 
heme group ?
Does someone knows how to fix it ?

Tanos Celmar Costa Franca - D.Sc
Coordenador do Programa de Pos-graduacão em Química
Secão de Engenharia Química - SE/5
Instituto Militar de Engenharia - IME
Rio de Janeiro - RJ
Brasil