\int rho(r) dx dy dz => \sum_{ijk} rho(i,j,k) \Omega/(nr1*nr2*nr3),
where \Omega = unit cell volume, nr*=FFT grid dimensions, i,j,k run over
FFT real-space grid points.Paolo On Thu, May 26, 2016 at 1:44 AM, reza vatan <[email protected]> wrote: > Dear all, > > I have one hydrogen molecule in a unit cell repeating in 3D space in such > a way non of the hydrogen molecules can't see each other. I'm trying to > calculate the "electron (pseudo-)charge density" in the entire unit cell > using pp.x. The problem is that when I add the charge density of all meshes > to get the total charge density of the entire unit cell I get different > values depends on the used grid. For instance, when I use 45x45x45 grid I > get 86.25 for charge density, but when I use 72x72x72 I get 353.26. > > However, since my unit cell size is 20.37x20.37x20.37 bhor^3 and I have 2 > electrons in the unit cell, I think I should get > 2/(20.37x20.37x20.37)=0.000236623. Does any one know why I'm not getting > this number? > > Thanks in advances, > > Best, > Reza Vatan, > Electrical Engineering Department, > Arizona State University. > > _______________________________________________ > Pw_forum mailing list > [email protected] > http://pwscf.org/mailman/listinfo/pw_forum > -- Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche, Univ. Udine, via delle Scienze 208, 33100 Udine, Italy Phone +39-0432-558216, fax +39-0432-558222
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