Is it correct to use different values of K in an umbrella sampling for different windows?

GROMACS version: 2019.3
GROMACS modification: No
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Hi, I simply want to know if it’s reasonable to use different values of force constant (pull-coord1-k) for some of the windows (with specific reaction coordinates) in an umbrella sampling simulation.

The reason is my groups attract each other with very high forces so I need to use higher K when two groups are close to each other. But I’m not sure if causes inaccuracy in following WHAM calculations.

Kind regards,


Hi Ehsan,

In theory this should be fine, because you know exactly the potential that you are adding, but in practice this is fidgety and the tools don’t take it too well. That type of optimization is done in a (what I think) neater way with AWH


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