No, it does not depend on the system content, aside from the mass of the particle. For a simulation requiring numerical integration in time, there is a limit, and I just estimated it above. For the real world, the limit is that there's no such thing as a harmonic position restraint. :) If you want to be really hardcore about it, and still assume there _is_ such a thing as harmonic restraints, then the "timestep" of the real world is your Planck's time. :)
Alex On Tue, Apr 21, 2015 at 1:36 PM, Marcelo Depólo <marcelodep...@gmail.com> wrote: > Thanks Alex. But then, theoretically, is there no limit? All depends on > your system's content, right? > > 2015-04-21 16:16 GMT-03:00 Alex <nedoma...@gmail.com>: > > > Correction: tau/pi on the left for the highest value and 5*tau/pi for the > > 10 x period suggestion above. > > > > On Tue, Apr 21, 2015 at 1:13 PM, Alex <nedoma...@gmail.com> wrote: > > > > > I think this can be estimated from a general physical argument. The > > > absolute max in my opinion should come from > > > 4*pi*tau = sqrt(m/k), where m is the mass of the lightest restrained > > > particle in the system, k is the constant you seek, and tau is the > > > timestep. > > > The coefficient is four because of the Nyquist theorem. I believe GMX > > > tests for high vibrational frequencies according to 20*pi*tau on the > left > > > (ten times the period). > > > > > > Hope this helps. > > > > > > Alex > > > > > > > > > On Tue, Apr 21, 2015 at 1:02 PM, Marcelo Depólo < > marcelodep...@gmail.com > > > > > > wrote: > > > > > >> Hi guys! > > >> > > >> Is there a maximum value of Force Constant for Position restraints? > > >> Reading > > >> the Manual I could only find the default and the equation to describe > > it. > > >> > > >> Best, > > >> -- > > >> Marcelo Depólo Polêto > > >> Group of Structural Bioinformatics - Center of Biotechnology > > >> Student of MSc Cell and Molecular Biology - UFRGS (Brazil) > > >> B.Sc. Biochemistry - University of Viçosa (Brazil) > > >> -- > > >> 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. > > > > > > -- > Marcelo Depólo Polêto > Group of Structural Bioinformatics - Center of Biotechnology > Student of MSc Cell and Molecular Biology - UFRGS (Brazil) > B.Sc. Biochemistry - University of Viçosa (Brazil) > -- > 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.