Well ... I dont have much information about your system ... Is it a molecule? Or a polymer maybe?
Anyway ... I dont know if it makes much sense calculating organic solids with GGA. The solid state in such materials is highly dependent on dispersion interactions like van der walls and london forces, which are not described by GGA. Thus, I would not be suprised with large cell parameters in this cases. Some guys I know correct it by ading an empirical Lenard-Jones like potential in the system ... but ...it is something "ad hoc". Cheers Ney On Tue, Jun 16, 2009 at 10:40 AM, Sridhar Neelamraju < neelamraju.srid...@gmail.com> wrote: > I imagine siesta uses primitive (Wigner-Seitz)cell parameters whereas > experimentalists prefer crystallographic units. Could someone else confirm > the same please? > > 2009/6/16 samtong <zjx...@gmail.com> > > Deal all, >> Attached is the .fdf file. >> The Pseudopotencial and basis sets of C, H, O, N, S in the system are >> downloaded from siesta website. But the calculated lattice parameters are >> almost doubled than experimental value. Could anyone tell me where i am >> wrong? Thank u very much. >> >> Chales >> > > > > -- > Sridhar Neelamraju > PhD Student, Jansen Group > Max-Planck-Institute for Solid State Chemistry > Stuttgart, Germany - 70569 > > E-mail:s.neelamr...@fkf.mpg.de <e-mail%3as.neelamr...@fkf.mpg.de> > Landline: (+49)0711-12164749 > Mobile: (+49) 0176-70128213 >
