On Wed, 2009-05-27 at 14:33 +0200, Yan Chai wrote: > It seems that in the twin range cut-off method, rlist does not only > play a role as a cut-off for neighbor searching, but also as a cut-off > for short-range interactions. Do I understand correctly?
If you're using Coulombic cutoffs, then yes. If you're using PME, then AFAIK the part r > rcut will be performed in Fourier space. > Do people think the effect of these inward moving and outward moving > particles is small and the error for calculation can be tolerated? When particles move in and out of the cutoff range it induces static in the properties. Ideally for monocomponent systems (such as metals) the cutoff should be in an (absolute) minimum of the pair correlation function, i.e. there aren't many particles in the region where the cutoff is made. For molecular systems the decision of a cutoff is harder, since some pair correlations stay quite constant and there is no clear cut way to make the decision. The farther you go the fewer static you get. Roughly speaking, the number of particles at cutoff range grows as r_cut^2, but for Lennard-Jones the interaction weakens as r_cut^-6, resulting in an error proportional to r_cut^-4. -- ------------------------------------------------------ Jussi Lehtola, FM, Tohtorikoulutettava Fysiikan laitos, Helsingin Yliopisto jussi.leht...@helsinki.fi, p. 191 50632 ------------------------------------------------------ Mr. Jussi Lehtola, M. Sc., Doctoral Student Department of Physics, University of Helsinki, Finland jussi.leht...@helsinki.fi ------------------------------------------------------ _______________________________________________ gmx-users mailing list gmx-users@gromacs.org http://www.gromacs.org/mailman/listinfo/gmx-users Please search the archive at http://www.gromacs.org/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/mailing_lists/users.php
