CATDCD program can be used to convert one file format to another file format. For example: How to convert trajectory output of GROMACS .xtc format into NAMD .dcd format ==== /path/to/catdcd -o /path/to/save/file/abc.dcd -xtc /input/path/to/save/file/abc.xtc ==== How to install CATDCD? Follow the link- https://www.ks.uiuc.edu/Development/MDTools/catdcd/ Download the catdcd-X.Xx.tar.gz Extract all files from the tar. Locate the catdcd file. It should be in directory : catdcd-4.0b/LINUXAMD64/bin/catdcd4.0/ Source the catdcd in your bashrc: export PATH="/path/to/catdcd/directory/:$PATH"