On Oct 11, 2013 7:59 PM, "Guillaume Chevrot" <guillaume.chev...@gmail.com> wrote: > > Hi all, > > I recently compared the total energy of 2 simulations: > lysozyme in water / NVE ensemble / single precision > lysozyme in water / NVE ensemble / double precision > > ... and what I found was quite ... disturbing (see the attached figure - > plots of the total energy). I observe a constant drift in energy in the > case of the single precision simulation. > > Did I do something wrong*? Any remarks are welcomed! I join the ‘mdout.mdp’ > file so you can check what mdp options I used.
Maybe. Unfortunately we cannot configure the mailing list to allow people to send attachments to thousands of people, so you will need to do something like provide links to files on a sharing service. > > My second question is: if I did not do something wrong, what are the > consequences on the simulation? Can I trust the results of single precision > simulations? Yes, as you have no doubt read in the papers published by the GROMACS team. > Regards, > > Guillaume > > *PS: I am not the only one encountering this behavior. In the literature, > this problem has already been mentioned: > http://jcp.aip.org/resource/1/jcpsa6/v126/i4/p046101_s1 ... which is six years old, examining the properties of code seven years old. Life has moved on! :-) Even if you have found a problem, it is a big assumption that this is (still) the cause. Mark > -- > 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 -- 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