> You need some ions to neutralise the system for long range electrostatics to work.
This mostly applies to PME. However, because PME is basically *de facto* nowadays, it will most likely apply in most situations. However, I recently learned that PME can also be run with a non-neutral system, as PME will introduce a neutralizing background charge (and dipole corrections). Here is the thread: https://www.mail-archive.com/gromacs.org_gmx-users@maillist.sys.kth.se/msg29536.html > We usually add more to make the simulation more like the real system (solution or cell). Just to be the devil's advocate, I'd say that based on anecdotal evidence adding salt in a MD simulation of a protein changes make little to no difference. It doesn't behave as expected, most likely due to poor ion parametrization and integer charges. J On Sun, Jan 21, 2018 at 7:16 AM, <jamesmkrie...@gmail.com> wrote: > You need some ions to neutralise the system for long range electrostatics > to work. We usually add more to make the simulation more like the real > system (solution or cell). > > > On Jan 21, 2018, at 1:12 AM, Sankaran SV . <119013...@sastra.ac.in> > wrote: > > > > Dear all, > > > > I am a beginer. I would like to know the purpose of adding > ions > > during the simulation process. > > -- > > 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. > -- > 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. > -- 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.
