[gmx-users] umbrella sampling with pull=constraint

Hello, I have done umbrella sampling with pull=umbrella and I found that the pulling group has high fluctuations and sometimes moving out of the periodic box. I think that the harmonic potential is not properly applied and thus the pulling group is not retained with the specified COM distance

[gmx-users] umbrella sampling with pull=constraint

Dear Vijay: Can you please provide evidence for your claim that the harmonic potential is not applied properly, since you may decide to use pull=umbrella once you have set that up correctly. Importantly, movement out of the unit-cell is not a problem, as discussed a lot on this list.