[Pw_forum] Fwd: Fwd: shape of real space wave functions in wfc2kr

[Lorenzo Paulatto]

On 28 September 2017 at 19:54, Jacopo Simoni <simonij at tcd.ie> wrote:


>
> r_ijk(:) = (i-1)/dffts%nr1x * a_1(:) + (j-1)/dffts%nr2x * a_2(:) +
> (k-1)/dffts%nr3x * a_3(:) ?
> with a_1, a_2, a_3 lattice parameters (I have a simple cubic cell), this
> is what I have found looking around in the documentation. In particular
> this is what it is written in the developer manual. The issue is that in
> the wfck2r program the real space grid does not appear explicitly so I am
> wondering if the previous expression for the wave function index is still
> usable.
>
>

Almost, you have this kind of code in add_efield, for the hard grid but
applies jus tthe same to the smooth grid. Be careful that nr1x, nr2x and
nr3x are the dimensions of the FFT which can be (but almost never are)
bigger than the physical dimension of the cell, which are actually nr1, nr2
and nr3. So you should use the latter, and eventually throw away the points
which fall outside the physical range.

Also, be careful when doit it in parallel, each CPU has a share of the
planes of charge along Z, hence he box dimension along that direction is
nr3, but the actual number of points on a CPU is dfftp%my_nr3p and the
index of the first plane is dfftp%my_i0r3p.

hth



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-- 
Lorenzo Paulatto - Paris
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