---
name: "obrotamer"
section: "1"
platform: "linux"
package: "openbabel"
version: "3.2.1-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/obrotamer"
---

# obrotamer(1)

generate conformer/rotamer coordinates

## NAME

**obrotamer** – generate conformer/rotamer coordinates

## SYNOPSIS

**obrotamer** *filename*

## DESCRIPTION

The **obrotamer** tool can be used as part of a conformational search by generating random isomers based on rotating dihedral angles. These rotamers are not conformers — that is, **obrotamer** does not perform geometry optimization after generating the rotamer structure. The obminimize tool can do geometry optimization using molecular mechanics.

## ENVIRONMENT

- OB\_RANDOM\_SEED

  Seed for pseudo random number generator; random seed is used if unset or null. This feature is effective if Open Babel is built with *-DOB\_USE\_OBRANDOMMT* cpreprocessor flag (will be automatically enabled when version 4 is released).

## EXAMPLES

```
obrotamer baseconformer.sdf > rotamer1.sdf
```

Generate a random rotational isomer of baseconformer.sdf and write it to rotamer1.sdf

## SEE ALSO

[obabel(1)](/obabel/1.md), [obenergy(1)](/obenergy/1.md), [obfit(1)](/obfit/1.md), [obgrep(1)](/obgrep/1.md), [obminimize(1)](/obminimize/1.md), [obrotate(1)](/obrotate/1.md).

The web pages for Open Babel can be found at: \<**https://openbabel.org/**\>

## AUTHORS

Open Babel is developed by a cast of many, including current maintainers Geoff Hutchison, Chris Morley, Michael Banck, and innumerable others who have contributed fixes and additions. For more contributors to Open Babel, see \<**https://openbabel.org/docs/Introduction/thanks.html**\>

## COPYRIGHT

Copyright (C) 1998-2001 by OpenEye Scientific Software, Inc.\
 Some portions Copyright (C) 2001-2007 by Geoffrey R. Hutchison and other contributors.

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation version 2 of the License.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.