[gmx-users] Umbrella Sampling and histograms smoothness

[Agnivo Gosai]

Dear Users

My umbrella sampling simulations are of 1 ns time whereas Dr. Lemkul's
tutorial advocates a 10 ns simulation time. I found that after running WHAM
, my histograms are coarser ( rough) compared to Dr. Lemkul's. A few of my
histograms have two peaks!!
So should I increase the simulation time from 1 ns to 10 ns ?? I do a 100
ps NPT equilibration and then a 1 ns umbrella sampling in each of my
windows. The generated PMF curve is also not smooth and is discontinuous at
one position which I think I can fix by adding more windows around that
co-ordinate.

A picture is linked : ​
 HISTO
<https://docs.google.com/file/d/0B-U8uULVZjfRQXcyUkI2bXhBcVE/edit?usp=drive_web>
​
Kindly help.

Thanks & Regards
Agnivo Gosai
Grad Student, Iowa State University.