---
name: "gmx-convert-tpr"
section: "1"
platform: "linux"
package: "gromacs-data"
version: "2025.2-1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/gmx-convert-tpr"
---

# gmx-convert-tpr(1)

Make a modified run-input file

## NAME

gmx-convert-tpr - Make a modified run-input file

## SYNOPSIS

```
gmx convert-tpr [-s [<.tpr/.gro/...>]] [-n [<.ndx>]]
             [-o [<.tpr/.gro/...>]] [-extend <time>] [-until <time>]
             [-nsteps <int>] [-[no]generate_velocities]
             [-velocity_temp <real>] [-velocity_seed <int>]
```

## DESCRIPTION

**gmx convert-tpr** can edit run input files in three ways.

**1.** by modifying the number of steps in a run input file with options **-extend**, **-until** or **-nsteps** (nsteps=-1 means unlimited number of steps)

**2.** by creating a .tpx file for a subset of your original tpx file, which is useful when you want to remove the solvent from your .tpx file, or when you want to make e.g. a pure Calpha .tpx file. Note that you may need to use **-nsteps -1** (or similar) to get this to work. **WARNING: this .tpx file is not fully functional**.

**3.** by setting the charges of a specified group to zero. This is useful when doing free energy estimates using the LIE (Linear Interaction Energy) method.

## OPTIONS

Options to specify input files:

- **-s \[\<.tpr/.gro/...\>\] (topol.tpr)**

  Run input file to modify: *tpr* *gro* *g96* *pdb* brk ent

- **-n \[\<.ndx\>\] (index.ndx) (Optional)**

  File containing additional index groups

Options to specify output files:

- **-o \[\<.tpr/.gro/...\>\] (tprout.tpr) (Optional)**

  Generated modified run input file: *tpr* *gro* *g96* *pdb* brk ent

Other options:

- **-extend \<time\> (0)**

  Extend runtime by this amount (ps)

- **-until \<time\> (0)**

  Extend runtime until this ending time (ps)

- **-nsteps \<int\> (0)**

  Change the number of steps remaining to be made

- **-\[no\]generate\_velocities (no)**

  Reassign velocities, using a generated seed unless one is explicitly set

- **-velocity\_temp \<real\> (300)**

  Temperature to use when generating velocities

- **-velocity\_seed \<int\> (-1)**

  Random seed for velocities. If value is -1, a new one is generated

## SEE ALSO

**[gmx(1)](/gmx/1.md)**

More information about GROMACS is available at \<*http://www.gromacs.org/*\>.

## COPYRIGHT

2025, GROMACS development team