[gmx-users] The Rg does not change at all during the umbrella sampling

[faride badalkhani]

Dear all,

I want to perform pulling simulations on a polymer-drug system. I have
performed simulations on polymer and polymer+drug for 30 ns and then set up
system for pulling. After generating configurations I chose some of them
and performed a 10 ns of MD for each window. However, when I plot the Rg
for the system it does not change during the simulation and autocorrelation
function of Rg is zero, as well.

I have performed another PMF simulation on a similar system (the only
difference is in the terminal groups of polymers) and I did not have this
problem. I would appreciate any suggestions on how to solve this issue.

Regards,
Farideh