Calculation of velocities

From: Eric Cyr (
Date: Tue Aug 31 2004 - 15:44:47 CDT

I need to calculate particle velocities in the applied forces scripting
interface, since no "loadvelocities" command exists. I've been trying
to use a centered difference (x(n+1) - x(n-1))/(2dt). However, I
my answers were incorrect. So I had NAMD dump ASCII restart files
and looked at the values calculated by them. Even when accounting
for the PDBVELFACTOR the values I calculated for the velocities were
about 1/50th of what they should be. I've been trying to figure out
the difference could possibly be. Any suggestions?

Thanks for any help

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