Re: Harmonic force Keyword "centers" significance

From: Vermaas, Joshua (
Date: Wed Jun 21 2017 - 17:49:20 CDT

It defines the value for the collective variable around which the
umbrella is "centered". Lets say the current value for the collective
variable is 5 with a center of 10 and a force constant of 2. The value
for the potential at that point would be 2*(5-10)^2. In short, the
"center" is just the point where the potential has a value of 0.


On 06/21/2017 04:45 PM, Rabeta Yeasmin wrote:
> Dear NAMD users,
> I am trying to restrain the distance between two residue during the
> umbrella sampling simulation. I have plan to use colvar and harmonic
> force to do this. I believe "distance" option of colvar can do this.
> But I can not understand the significance of the keyword centers in
> harmonic force section. What is its role here?
> I will be grateful if anyone can help me to find out this.
> Thanks.
> Regards
> Rabeta Yeasmin

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