[QE-users] 3d-rho resolution

[Tone Kokalj]

Dear Alexandra,

You always get the same result because output_format = 6 (cube file)
just dumps the density on the FFT grid, which depends on the ecutrho in
pw.x input file.

This implies you have three options:

either
1. recipe of Giuseppe via nr1, nr2, nr3 with pw.x + pp.x sequence
or
2. stepwise increase ecutrho and run pw.x + pp.x sequence
or
3. use output_format = 3 (XSF file, slow option with user supplied 3D region)

Note that option 3 is very slow; options 1 & 2 are faster.
 
Rest regards,
Tone
-- 
Jožef Stefan Institute, Ljubljana, Slovenia


On Tue, 2023-01-10 at 05:53 +0300, Aleksandra Oranskaia wrote:
> Dear users and developers,
> 
> I am trying to generate more and less accurate electron density cubes
> (to study how some properties, extracted from cubes, depend on their
> resolution) but fail somewhere.
> 
> Here is the pp.x input:
> &INPUTPP
> prefix = myinput
> filplot = myinput.rho
> plot_num = 0
> /
> &PLOT
> nfile = 1
> filepp(1) = myinput.rho
> iflag = 3
> output_format = 6
> !e1(1) = 1, e1(2) = 0, e1(3) = 0
> !e2(1) = 0, e2(2) = 1, e2(3) = 0
> !e3(1) = 0, e3(2) = 0, e3(3) = 1
> x0(1) = 0, x0(2) = 0, x0(3) = 0
> nx = 1000, ny = 1000, nz = 1000
> fileout = myinput.cube
> /
> 
> Regardless of nx, ny, and nz (e.g. 50, 50, 50 vs 1000, 1000, 1000) I
> get the same outputs. What should I change to generate cubes with
> different resolutions? Parameters in SCF are very accurate, so my
> guess: It is pp.x input lines. not pw.x parameters.
> 
> Thank you in advance!
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