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

# gmx-gyrate(1)

Calculate radius of gyration of a molecule

## NAME

gmx-gyrate - Calculate radius of gyration of a molecule

## SYNOPSIS

```
gmx gyrate [-f [<.xtc/.trr/...>]] [-s [<.tpr/.gro/...>]] [-n [<.ndx>]]
           [-o [<.xvg>]] [-b <time>] [-e <time>] [-dt <time>]
           [-tu <enum>] [-fgroup <selection>] [-xvg <enum>]
           [-[no]rmpbc] [-sf <file>] [-selrpos <enum>]
           [-seltype <enum>] [-sel <selection>] [-mode <enum>]
```

## DESCRIPTION

**gmx gyrate** computes the radius of gyration of a molecule and the radii of gyration about the *x*-, *y*- and *z*-axes, as a function of time. The atoms are explicitly mass weighted.

The axis components corresponds to the mass-weighted root-mean-square of the radii components orthogonal to each axis, for example:

Rg(x) = sqrt((sum\_i w\_i (R\_i(y)^2 + R\_i(z)^2))/(sum\_i w\_i)).

where w\_i is the weight value in the given situation (mass, charge, unit)

Note that this is a new implementation of the gyrate utility added in GROMACS 2024. If you need the old one, use **gmx gyrate-legacy**.

## OPTIONS

Options to specify input files:

- **-f \[\<.xtc/.trr/...\>\] (traj.xtc) (Optional)**

  Input trajectory or single configuration: *xtc* *trr* *cpt* *gro* *g96* *pdb* *tng*

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

  Input structure: *tpr* *gro* *g96* *pdb* brk ent

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

  Extra index groups

Options to specify output files:

- **-o \[\<.xvg\>\] (gyrate-taf.xvg)**

  Filename for gyrate plot output

Other options:

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

  First frame (ps) to read from trajectory

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

  Last frame (ps) to read from trajectory

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

  Only use frame if t MOD dt == first time (ps)

- **-tu \<enum\> (ps)**

  Unit for time values: fs, ps, ns, us, ms, s

- **-fgroup \<selection\>**

  Atoms stored in the trajectory file (if not set, assume first N atoms)

- **-xvg \<enum\> (xmgrace)**

  Plot formatting: xmgrace, xmgr, none

- **-\[no\]rmpbc (yes)**

  Make molecules whole for each frame

- **-sf \<file\>**

  Provide selections from files

- **-selrpos \<enum\> (atom)**

  Selection reference positions: atom, res\_com, res\_cog, mol\_com, mol\_cog, whole\_res\_com, whole\_res\_cog, whole\_mol\_com, whole\_mol\_cog, part\_res\_com, part\_res\_cog, part\_mol\_com, part\_mol\_cog, dyn\_res\_com, dyn\_res\_cog, dyn\_mol\_com, dyn\_mol\_cog

- **-seltype \<enum\> (atom)**

  Default selection output positions: atom, res\_com, res\_cog, mol\_com, mol\_cog, whole\_res\_com, whole\_res\_cog, whole\_mol\_com, whole\_mol\_cog, part\_res\_com, part\_res\_cog, part\_mol\_com, part\_mol\_cog, dyn\_res\_com, dyn\_res\_cog, dyn\_mol\_com, dyn\_mol\_cog

- **-sel \<selection\>**

  Select group to compute gyrate radius

- **-mode \<enum\> (mass)**

  Atom weighting mode: mass, charge, geometry

## SEE ALSO

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

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

## COPYRIGHT

2025, GROMACS development team