Dear gmx-users, I have run some tests (especially) for pure water, being able to achieve pretty much perfect energy conservation in NVE ensemble (with PME-switch and shifted VDW potential).
Then, just for the test, I continued to NVT ensemble by using previous .tpr and .cpt files, but the result was a quite surprise, because there seems to be constant drift in "Conserved En.". The drift (100kJ/mol = 0.3%) is not especially large, but it exists with v-rescale temperature coupling. On the other hand, there is no drift at all, if I change to nose-hoover temperature coupling. The behavior is similar also my other systems (liquid mixtures), even though then neither of temperature coupling methods will give exactly perfect conservation, but nose-hoover gives much better one (500 kJ/mol = 3% vs. 60 kJ/mol = 0.4%). Actually, I was expecting to see no drift at all, after all systems behaved fine in NVE ensemble with same parameters with an exception of added temperature coupling (especially when I used double precision for test purpose). So, the main question is, if it is just normal that even such parameters, which give perfect energy conservation in NVE ensemble may introduce drift in "Conserved En.", when NVT ensemble is used? Or is it just purely (only reason for drift) indication that some temperature coupling methods"work better" than others in this sense? Regards, Janne Hirvi-- gmx-users mailing list gmx-users@gromacs.org http://lists.gromacs.org/mailman/listinfo/gmx-users * Please search the archive at http://www.gromacs.org/Support/Mailing_Lists/Search before posting! * Please don't post (un)subscribe requests to the list. Use the www interface or send it to gmx-users-requ...@gromacs.org. * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists
