[Pw_forum] Increasing FFT grid for charge density analyses

Paolo Giannozzi giannozz at democritos.it
Tue Aug 2 10:54:11 CEST 2011

On Tue, 2011-08-02 at 10:38 +0200, Sven Heiles wrote:

> As far as I understand the input I do that by changing nx,ny,nz. If I do
> so no matter if I use 40,40,40; 60,60,60 or 120,120,120 the cube file always
> consists of a 240x240x240 grid.

there are only a few (documented) cases in which you can use your own
grid instead of the FFT grid. These cases are implemented using a 
"Slow" FT. If you try this on a 120x120x120 grid, it will take more
time that the rest of the calculation.

Paolo Giannozzi, IOM-Democritos and University of Udine, Italy

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