[gmx-users] xtc file and trr file

[Mark Abraham]

On 17/08/2012 6:46 PM, Acoot Brett wrote:
> Dear All,
>
> After a production MD, both the xtc file and trr file are produced. trr file is much larger than the xtc file. But when we openned the original gro file one of the file from xtc file and trr file in VMD, we will find the xtc contains more frames in comparison with the trr file.
>
> Will you please explain why xtc file is smaller file than the trr file, but the xtc file contains more frames in VMD?

Clearly one format is more efficient at storing frames than the other. 
They have different numbers of frames because that's what you asked for 
in your .mdp file (unless you've post-processed).

Mark