Why "fixedAtomsForces on" for constant pressure?

From: Jan Saam (jan.saam_at_rz.hu-berlin.de)
Date: Tue Nov 25 2003 - 18:30:09 CST

Hi all,

When you are trying to simulate a system using constant pressure then NAMD
requires that all forces, including the ones between fixed atoms are
calculated ("fixedAtomsForces on").
I assume this is somehow due to the the pressure calculation scheme that uses
the atomic virial and kinetic energy.
But couldn't one just take omly the moving atoms into account?

I remember that "fixedAtomsForces on" was not required in former versions of
NAMD. How did it work then?

Does anybody know about this?



Jan Saam
Institut für Biochemie
Monbijoustr. 2
10117 Berlin
030-450 528 449

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