Restraining the mass centre coordinate during Umbrella Sampling

From: Rabeta Yeasmin (
Date: Wed Jun 07 2017 - 10:46:57 CDT


Sorry, I have posted the same question yesterday but did not get any
response yet. I can not proceed umbrella sampling without that information.
That's why I am posting it again-

I am trying to do umbrella Sampling of a protein-lipid system. I have
created several windows by putting the protein at different distance along
z-axis from the lipid and equilibrated each system restraining the center
of mass of both protein and lipid.
Now I am trying to run the simulation for each window. Should I restrain
all the coordinates (x, y, z) of the center of mass of the protein and
lipid or just only z coordinate? I have seen some posts here where they
restrain all coordinates of center of mass while in some post, they said
only to restrain z coordinate.

In the configuration file from NAMD tutorial, they also restrain the z
coordinates using constraints by applying force to some selected atoms. Is
it necessary if I already restrain the coordinates in colvar file?

If anyone have any idea about this, please help me.


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