Hi, 1. No. 2. From the look of https://github.com/gromacs/gromacs/blob/master/src/gromacs/gmxpreprocess/nm2type.cpp#L91, you could supply as many as fits in a double-precision value (maybe about 15), but whether the subsequent calculations retain the precision is unclear without a detailed look at the code. I suggest you construct a toy case with three particles whose charge is 0.333333333333333 and one of them has a last digit of 4 and see how you go.
Mark On Thu, Sep 27, 2018 at 11:40 AM Alex <nedoma...@gmail.com> wrote: > Hm, i thought it was a question someone could answer... > > > On Sat, Sep 22, 2018, 10:52 PM Alex <nedoma...@gmail.com> wrote: > > > Hi all, > > > > I am dealing with a solid structure with partial charges initially > > obtained from DFT and adjusted to work with MD. It just so happens that > > the total charge of the system, however small, will always be nonzero. > > The reason is trivial and unfortunately unavoidable, given the > > geometries. It sounds silly, but this is the situation. It has to do > > with division by three and one of the partial charges will have to have > > the form of e.g. 0.333333... Hence, a few questions: > > > > 1. Is the total charge of the system of the order ~1e-6 expected to > > produce artifacts with the latest versions of GMX (we're using 2018.1)? > > > > 2. The total charge will go down with the number of digits readable by > > x2top from atomname2type, so what's the max number of digits I could > > supply? > > > > Thanks, > > > > Alex > > > > > -- > 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.