DCD Files

The file TRAJEC.dcd contains the coordinates of the system in X-Plor, CHARMM style binary format. This is especially convenient for large systems (QM/MM) or long trajectories, since binary files load much faster and the file needs much less storage. Unlike the other trajectory formats supported by CPMD, DCD format files also contain supercell size and shape information, so periodic display is easier. On the other hand, DCD files contain no information about elements, so in programs like VMD, one first has to load, e.g., the GEOMETRY.xyz file and then load the coordinates from the DCD file on top of that. It may also be advantageous to first generate a PSF format file to define elements and bonding information.