Rerun does not calculate reciprocal energies - Redmine #3400
A student in our group found that using rerun in GROMACS 2019, neither the Coulomb nor the LJ reciprocal terms are recalculated. These energies are 0, and consequently, the potential energy is missing these terms and is off compared to the original run.
The bug can be retraced to #1868, where rerun was split off and
restricted to explicitly only calculate forces and potential energies,
omitting kinetic energies, virial, pressure, constraints, etc.
Consequently, within do_rerun, do_force did not get the
GMX_FORCE_VIRIAL flag anymore. In gmx_pme_do, called from the lower
level functions within do_force, the reciprocal terms are however only
calculated if GMX_FORCE_VIRIAL was originally passed. I don’t see a
compelling reason why reciprocal energy terms and virial should be
intimately linked, but maybe I’m overlooking a detail here.
Note that due to #2649, the GMX_FORCE_VIRIAL flag was reintroduced if
GROMACS was compiled with GPU support, so GPU enabled builds are not
affected by this bug.
The easy solution to fix this bug is to pass GMX_FORCE_VIRIAL in all
cases. Moving forward, we should check whether these options can be
disentangled.
(from redmine: issue id 3400, created on 2020-02-25 by ptmerz, closed on 2020-02-28)
- Relations:
- relates #1868 (closed)
- relates #2649 (closed)
- Changesets:
- Revision cc055a76 on 2020-02-26T02:15:09Z:
Fix calculation of reciprocal terms in rerun
This at least temporarily fixes #3400.
Change-Id: I04d67d9bb3edbd66049573de71940e4bb7fa1ad4