This plugin reads molecular coordinate data stored in CHARMM Cartesian Coordinate format. More information about this file format can be found below.

Note that the files created by CHARMM normally carry the extension .crd. Since this extension is also used by Amber 7 trajectory files, the filetype must be explicitly set to cor when opening a Cartesian Coordinate File in VMD. This extra step can be omitted by renaming the file and changing the the extension to cor.


This plugin is used only to read files. VMD does not currently support writing this file type.

Unused data
The Weight field, which can be used to store atom-dependent data such as mass or charge is ignored by VMD.

ASCII format
This plugin reads only ASCII, or "formatted" COOR files. Binary coordinated files produced by CHARMM are presently not supported by VMD.

Format of the CHARMm coordinate file

CHARMm coordinate files contain information about the location of each atom in Cartesian (3D) space. The format of the ASCII (CARD) CHARMm coordinate files is:
    * Title line(s)
    * Number of atoms in file
    * Coordinate line (one for each atom in the file)

The coordinate lines contain specific information about each atom in the model and consist of the following fields:
    * Atom number (sequential)
    * Residue number (specified relative to first residue in the PSF)
    * Residue name
    * Atom type
    * X-coordinate
    * Y-coordinate
    * Z-coordinate
    * Segment identifier
    * Residue identifier
    * Weighting array value

The FORTRAN FORMAT statement for the coordinate lines is:

I5, I5, 1X, A4, 1X, A4, 3(F10.5), 1X, A4, 1X, A4, F10.5