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Created by Paul Bauer@acmnpvOwner

coul-lambda affects the pressure computation of a ligand with zero partial charge - Redmine #2640

Archive from user: zhiyi wu

This is a simplified and corrected version of the issue 2600.
I’m trying to compute the decoupling free energy of vdw interactions of a ligand which has zero partial changes.
Since the ligand has zero partial, changing coul-lambda shouldn’t have any effect on anything.
However, setting coul-lambda to 0 yields a pressure 2.13121e+02 bar of whereas setting coul-lambda to 1 yeilds a pressure of 1.07168e+02 bar.
The commands to reproduce the results are
gmx grompp -f coul-lambdas_0.mdp -c prod.gro -o coul-lambdas_0.tpr
gmx mdrun -deffnm coul-lambdas_0 -rerun prod.gro
gmx grompp -f coul-lambdas_1.mdp -c prod.gro -o coul-lambdas_1.tpr
gmx mdrun -deffnm coul-lambdas_1 -rerun prod.gro

If you compare the pressure in coul-lambdas_1.edr and coul-lambdas_0.edr, you will notice that the pressure are different whereas they should be the same.

(from redmine: issue id 2640, created on 2018-09-07 by gmxdefault, closed on 2018-09-27)

Fix PME forces with FE without perturbed q/LJ

PME would incorrectly scale the mesh forces with lambda when no
charges or LJ atom types were actually perturbed.

Fixes #2640

Change-Id: I193d55cf76d842f5b04d3a220411282c06b08a90
  • Revision a507acbc by Berk Hess on 2020-02-04T10:05:04Z:
Actually fix PME forces with FE without perturbed q/LJ

PME would incorrectly ignore the mesh forces on perturbed atoms when
no charges or LJ atom types were actually perturbed.
This is because the "fix" in commit 12f01f79 incorrectly changed the
lambda value used for the PME forces from the actual lambda value
to 1 instead of to 0 as it should have been.

Fixes #2640
Fixes #3359

Change-Id: Ib19565bf017ddbd2fddc66c52be0ff9efc7e707c
  • Revision 7387a098 by Berk Hess on 2020-02-05T07:14:49Z:
Actually fix PME forces with FE without perturbed q/LJ

PME would incorrectly ignore the mesh forces on perturbed atoms when
no charges or LJ atom types were actually perturbed.
This is because the "fix" in commit 12f01f79 incorrectly changed the
lambda value used for the PME forces from the actual lambda value
to 1 instead of to 0 as it should have been.

Fixes #2640
Fixes #3359

Change-Id: Ib19565bf017ddbd2fddc66c52be0ff9efc7e707c