[gmx-users] accleration group

Rui Qiao ruiqiao at ews.uiuc.edu
Mon Jan 21 21:07:03 CET 2002

Dear All:
	Thanks for the prompt response of Erik and David.
	So I guess what Gormacs do is to put a force on the system so that
the net force is zero for the whole system, is this right?
	Actually I am trying to simulate flow in a channel (periodicity
is removed in z-direction by some cut-off scheme), and I use the
accleration as a way of making my fluid moving. On one hand, I freeze the
wall atoms, and on the other hand, I give an accleration to all the fluid
atoms. So there would be a center-of-mass velocity in my system and I put
	nstcomm  =  100000000 

	in the .mdp file so that the velocity is not removed.

	The questions are:
	1. Where does this correction actually applied on? Does it applies
on wall atoms or fluid atoms? The latter case would be a tough thing for
	2. If instead of freezing the wall, I constrait the wall atoms by
some spring, then how the correction will be done for the wall atoms? In
this case, the wall atoms will be pushed by the accleration, and this is
not wanted in the simulation actually. 

	Thanks a lot.


Rui Qiao
Research Assistant
Beckman Institute, UIUC

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