[gmx-users] fatal error with charmm/amber forcefield

Mark Abraham mark.j.abraham at gmail.com
Thu Aug 1 14:33:11 CEST 2013

On Wed, Jul 31, 2013 at 11:20 PM, Sanku M <msanku65 at yahoo.com> wrote:
> Dear Gromacs users,
>   I am using gromacs 4.5.4 .
>  Is there any known issue/problem in running hamiltonian replica exchange calculations or FEP  with charm27.ff or amber forcefield  in gromacs4.5.4 ?

Almost certainly. Do check out the release notes on the webpage.

> I tried running an hamiltonian replica exchange using charmm27.ff by interpolating A state and B state but it gives error that dihedral terms with multiple values can not be interpolated..One need to write all A and B states in topol.top manually.
>  With opls.ff , it does not have any such problem. It works fine... Is it resolved in gromacs 4.6

Answering that question would require a whole lot more detail from
you. You are better advised to install 4.6 and try it. :-)


> This is the series error I am getting when using charmm forcefield or amber forcefield:
> WARNING 1197 [file topol_scale.top, line 2353]:
>   No default Proper Dih. types for perturbed atoms, using normal values
> ERROR 323 [file topol_scale.top, line 2354]:
>   Cannot automatically perturb a torsion with multiple terms to different
>   form.
>   Please specify perturbed parameters manually for this torsion in your
>   topology!
> Any idea?
> Thanks
> Sanku
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