Re: PME for a hexagonal system

From: Nicholas M Glykos (
Date: Sat Dec 23 2006 - 04:28:09 CST

> Does anybody know how to figure out the PME grid size for a hexagonal
> system?

Assuming that x axis is the unique axis (the sixfold), and that the
respective axes lenghts are a, b and c (with b=c), then you will probably
need something in the spirit of :

cellBasisVector1 a 0.00 0.00
cellBasisVector2 0.00 b*sin(60) b*cos(60)
cellBasisVector3 0.00 0.00 c
cellOrigin 0.00 0.00 0.00

Pme on
PmeGridsizeX <nearest "good" FFTW number to (a) Angstroms>
PmeGridsizeY <nearest "good" FFTW number to (b) Angstroms>
PmeGridsizeZ <nearest "good" FFTW number to (c) Angstroms>

In other words, the PME grid sizes should correspond to the
'crystallographic' frame (and _not_ the orthogonal frame).


            Dr Nicholas M. Glykos, Department of Molecular 
        Biology and Genetics, Democritus University of Thrace,
    Dimitras 19, 68100 Alexandroupolis, GREECE, Fax ++302551030613
     Tel ++302551030620 (77620),

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