Generating unbaised PMF

GROMACS version: 2018.4
GROMACS modification: Yes/No
Dear all
I am reconstructing the unbaised PMF of ligand dissociation by gmx wham module. I am getting the following warning (shown in bold)
Reading pull force file umbrella0_pullf.xvg, expecting 2 columns:
Columns for pull coordinate 1
reaction coordinate: 1
center-of-mass of groups: 0
reference position column: No
Found 100001 times in umbrella0_pullf.xvg
Reading file umbrella73.tpr, VERSION 2018.4 (single precision)
Reading file umbrella86.tpr, VERSION 2018.4 (single precision)
Reading file umbrella90.tpr, VERSION 2018.4 (single precision)
Reading file umbrella106.tpr, VERSION 2018.4 (single precision)
Reading file umbrella131.tpr, VERSION 2018.4 (single precision)
Reading file umbrella145.tpr, VERSION 2018.4 (single precision)
Reading file umbrella152.tpr, VERSION 2018.4 (single precision)
Reading file umbrella167.tpr, VERSION 2018.4 (single precision)
Reading file umbrella181.tpr, VERSION 2018.4 (single precision)
Reading file umbrella214.tpr, VERSION 2018.4 (single precision)
Reading file umbrella230.tpr, VERSION 2018.4 (single precision)
Reading file umbrella250.tpr, VERSION 2018.4 (single precision)
Reading file umbrella274.tpr, VERSION 2018.4 (single precision)
Reading file umbrella287.tpr, VERSION 2018.4 (single precision)
Reading file umbrella309.tpr, VERSION 2018.4 (single precision)
Reading file umbrella327.tpr, VERSION 2018.4 (single precision)
Reading file umbrella339.tpr, VERSION 2018.4 (single precision)
Reading file umbrella374.tpr, VERSION 2018.4 (single precision)
Reading file umbrella402.tpr, VERSION 2018.4 (single precision)
Reading file umbrella411.tpr, VERSION 2018.4 (single precision)
Reading file umbrella425.tpr, VERSION 2018.4 (single precision)
Reading file umbrella447.tpr, VERSION 2018.4 (single precision)
Reading file umbrella461.tpr, VERSION 2018.4 (single precision)
Reading file umbrella499.tpr, VERSION 2018.4 (single precision)
Reading file umbrella500.tpr, VERSION 2018.4 (single precision)

Determined boundaries to 0.059854 and 0.937747

Reading file umbrella0.tpr, VERSION 2018.4 (single precision)
Reading file umbrella73.tpr, VERSION 2018.4 (single precision)
Reading file umbrella86.tpr, VERSION 2018.4 (single precision)
Reading file umbrella90.tpr, VERSION 2018.4 (single precision)
Reading file umbrella106.tpr, VERSION 2018.4 (single precision)
Reading file umbrella131.tpr, VERSION 2018.4 (single precision)
Reading file umbrella145.tpr, VERSION 2018.4 (single precision)
Reading file umbrella152.tpr, VERSION 2018.4 (single precision)
Reading file umbrella167.tpr, VERSION 2018.4 (single precision)
Reading file umbrella181.tpr, VERSION 2018.4 (single precision)
Reading file umbrella214.tpr, VERSION 2018.4 (single precision)
Reading file umbrella230.tpr, VERSION 2018.4 (single precision)
Reading file umbrella250.tpr, VERSION 2018.4 (single precision)
Reading file umbrella274.tpr, VERSION 2018.4 (single precision)
Reading file umbrella287.tpr, VERSION 2018.4 (single precision)
Reading file umbrella309.tpr, VERSION 2018.4 (single precision)
Reading file umbrella327.tpr, VERSION 2018.4 (single precision)
Reading file umbrella339.tpr, VERSION 2018.4 (single precision)
Reading file umbrella374.tpr, VERSION 2018.4 (single precision)
Reading file umbrella402.tpr, VERSION 2018.4 (single precision)
Reading file umbrella411.tpr, VERSION 2018.4 (single precision)
Reading file umbrella425.tpr, VERSION 2018.4 (single precision)
Reading file umbrella447.tpr, VERSION 2018.4 (single precision)
Reading file umbrella461.tpr, VERSION 2018.4 (single precision)
Reading file umbrella499.tpr, VERSION 2018.4 (single precision)
Reading file umbrella500.tpr, VERSION 2018.4 (single precision)

Back Off! I just backed up histo.xvg to ./#histo.xvg.1#
Wrote histo.xvg
Getting initial potential by integration.
Warning, poor sampling bin 191 (z=0.900436). Check your histograms!
Warning, poor sampling bin 192 (z=0.904826). Check your histograms!
Warning, poor sampling bin 193 (z=0.909215). Check your histograms!
Warning, poor sampling bin 194 (z=0.913605). Check your histograms!
Warning, poor sampling bin 195 (z=0.917994). Check your histograms!
Warning, poor sampling bin 196 (z=0.922384). Check your histograms!
Warning, poor sampling bin 197 (z=0.926773). Check your histograms!
Warning, poor sampling bin 198 (z=0.931163). Check your histograms!
Warning, poor sampling bin 199 (z=0.935552). Check your histograms!
Initialized rapid wham stuff (contrib tolerance 3.84615e-08)
Evaluating only 3884 of 5200 expressions.

   1) Maximum change 1.043909e-01
 100) Maximum change 1.285408e-05

Switched to exact iteration in iteration 136
Converged in 137 iterations. Final maximum change 8.71888e-07
Wrote profile2.xvg

In case you use results from gmx wham for a publication, please cite:

++++ PLEASE READ AND CITE THE FOLLOWING REFERENCE ++++
J. S. Hub, B. L. de Groot and D. van der Spoel
g_wham - A free weighted histogram analysis implementation including robust
error and autocorrelation estimates
J. Chem. Theory Comput. 6 (2010) pp. 3713-3720
-------- -------- — Thank You — -------- --------

GROMACS reminds you: “Don’t Push Me, Cause I’m Close to the Edge” (Tricky)

Hi,
you can look at the histogram histo.xvg and check where you need more sampling.
Best regards
Alessandra