Units in MD trajectory file

Tcl-ChemShell
1

Dear forum,

I’m using the dynamics module in Tcl-ChemShell and hopes to extract information from the outputed “dynamics.trj” file.

The coordinates are in a.u., while velocities and forces seem not. Could anyone tell me the unit of velocities and forces.

Best,
Jiawei

2

Hi Jiawei,

Although ChemShell’s units are normally in a.u., in the case of the MD-specific velocities and forces, DL_POLY’s internal conventions are retained (as the basis for Tcl-ChemShell’s MD driver). Velocities are in Ang/ps and forces are in Ang * Dalton/ps^2.

Best wishes,

Tom