---
name: "genpr"
section: "1"
platform: "linux"
package: "gromacs-data"
version: "3.3.3-2"
release: "Debian 5.0 (Lenny)"
platforms: ["linux"]
url: "https://new.carta.tech/genpr"
---

# genpr(1)

generates position restraints for index groups

## NAME

genpr - generates position restraints for index groups

## SYNOPSIS

**genpr** **-f** *conf.gro*  **-n** *index.ndx*  **-o** *posre.itp*  **-of** *freeze.ndx*  **-\[no\]h** **-nice** *int*  **-fc** *vector*  **-freeze** *real*

## DESCRIPTION

genpr produces an include file for a topology containing a list of atom numbers and three force constants for the X, Y and Z direction. A single isotropic force constant may be given on the command line instead of three components.

WARNING: genpr only works for the first molecule. Position restraints are interactions within molecules, therefore they should be included within the correct  **\[ moleculetype \]**

block in the topology. Since the atom numbers in every moleculetype in the topology start at 1 and the numbers in the input file for genpr number consecutively from 1, genpr will only produce a useful file for the first molecule.

The -of option produces an index file that can be used for freezing atoms. In this case the input file must be a pdb file.

## FILES

**-f** *conf.gro* **Input**\
  Generic structure: gro g96 pdb tpr tpb tpa xml

**-n** *index.ndx* **Input, Opt.**\
  Index file

**-o** *posre.itp* **Output**\
  Include file for topology

**-of** *freeze.ndx* **Output, Opt.**\
  Index file

## OTHER OPTIONS

**-\[no\]h**    *no*\
  Print help info and quit

**-nice** *int* **0**\
  Set the nicelevel

**-fc** *vector* **1000 1000 1000**\
  force constants (kJ mol-1 nm-2)

**-freeze** *real*      **0**\
  if the -of option or this one is given an index file will be written containing atom numbers of all atoms that have a B-factor less than the level given here

## SEE ALSO

**[gromacs(7)](/gromacs/7.md)**

More information about the **GROMACS** suite is available in **/usr/share/doc/gromacs** or at \<*http://www.gromacs.org/*\>.