[gmx-users] custom force constants

[Irem Altan]

Hi,

I am trying to create a position restraint file with custom force constants. The file looks like as follows:

; In this topology include file, you will find position restraint
; entries for all the heavy atoms in your original pdb file.
; This means that all the protons which were added by pdb2gmx are
; not restrained.

[ position_restraints ]
; atom  type      fx      fy      fz
1 2271 2271 2271
5 2202 2202 2202
7 2160 2160 2160
10 2523 2523 2523

etc.

However, when I’m trying to create an executable with grompp, I get the following error:

Fatal error:
Invalid position restraint type 2271
For more information and tips for troubleshooting, please check the GROMACS
website at http://www.gromacs.org/Documentation/Errors

The documentation does not list this error as far as I can see. Does this mean that intermediate values are not allowed? If so, what are the allowed values and what do they correspond to?

Best,
Irem