Hi all, I've been playing with g_tune_pme (neat tool!) for the last couple of days. If I understood correctly, it can also be used to iterate over different rcoulomb values using the -rmin and -rmax options. Using the Verlet scheme requires rvdw = rcoulomb, so I used the -scalevdw option (which should be true by default) to keep these equal. This does not seem to happen..
The (partial) contents of a tpr file of such a failed run show the following: verlet-buffer-drift = 0.005 * rlist = 1.213* rlistlong = 1.213 nstcalclr = 15 rtpi = 0.05 coulombtype = PME coulomb-modifier = Potential-shift rcoulomb-switch = 0 * rcoulomb = 1* vdwtype = Cut-off vdw-modifier = Potential-shift rvdw-switch = 0 * rvdw = 1.2* The original mdp has the following parameters: ; Neighborsearching ns_type = grid ; search neighboring grid cels nstlist = 15 ; 10 fs *rlist = 1.2 ; short-range neighborlist cutoff (in nm)* *rcoulomb = 1.2 ; short-range electrostatic cutoff (in nm)* *rvdw = 1.2 ; short-range van der Waals cutoff (in nm)* cutoff-scheme = Verlet ; Electrostatics coulombtype = PME ; Particle Mesh Ewald for long-range electrostatics pme_order = 4 ; cubic interpolation fourierspacing = 0.16 ; grid spacing for FFT I searched a bit in the source code of gmx_tune_pme.c (4.6.5) and found that the only check done between these parameters (rvdw and rcoulomb) is if rvdw != rcoulomb in the original file, keep them as is (line 875). Other than that, rvdw is checked against rlist to ensure that it keeps the highest value of the two (rvdw >= rlist) (line 1012). This seems to make sense since rlist was modified based on rcoulomb, in case of plain PME (line 1004). However, this only ensures both values are equal if the new rcoulomb is larger than the original. In case we start with rcoulomb 1.2 and ask g_tune_pme to range from 1.0 to 1.4, those below 1.2 will fail. Also, why is my rlist changing since it is equal to rcoulomb? It should be kept the same (line 1004) right? Am I doing something wrong here, which is totally possible.. or is there something that g_tune_pme is somehow missing? Cheers, João -- Gromacs Users mailing list * Please search the archive at http://www.gromacs.org/Support/Mailing_Lists/GMX-Users_List before posting! * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists * For (un)subscribe requests visit https://maillist.sys.kth.se/mailman/listinfo/gromacs.org_gmx-users or send a mail to gmx-users-requ...@gromacs.org.