Re: peridic boundary condition

From: Marc Q. Ma (
Date: Fri Mar 11 2005 - 13:15:31 CST


> There is a physical justification for using PBC, PBC conserve the
> momentum of the system. It is my understanding that without PBC
> conservation of momentum is violated.
> Ed

For conservative systems, conservation of momentum has nothing to do
with boundary conditions. For MD as is row, the forces are all pairwise
additive, and F12 = -F21. Momentum is strictly conserved. I am not sure
about polarizable force fields, I guesstimate it is still true.

When there is random force, such as the Langevin Pistons or heat
reservoirs, the momentum conservation is going to be violated at each
time step.


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