[Pw_forum] plane averaged local potential

[Gabriele Sclauzero]

Dear Eduardo and Ghosh,

Prasenjit Ghosh wrote:
> 
> 
> 2009/10/28 Eduardo Ariel Menendez Proupin <eariel99 at gmail.com 
> <mailto:eariel99 at gmail.com>>
> 
>     Hello,
>     I need to calculate plane averaged local potentials, and charges,
>     for a heterostructure. I.e., 
>     V(z)=1/(Lx*Ly) \int\int V(x,y,z) dx dy  
> 
>     I think I  can do it using PP to get V(x,y,z) in the 3D FFT grid and
>     a write a program that makes the average. Then I want to obtain the
>     macroscopic average, as defined in a triestine paper by Baldereschi,
>     Baroni and Resta PRL 61 ,734 (1988).
> 
>     Before spending one or two days  writing the program and become sure
>     that is works fine, I would like to confirm that this is not already
>     implemented in PP or in other utility of Quantum-ESPRESSO. 
> 
> Hi Eduardo,
> 
> The executable average.x can do the job........for the input file  you 
> can see the example on Work function calculation......
> However, if you want to calculate the planar average of charge density, 
> you need to multiply it with the area of the xy plane, assuming you want 
> to plot along the z-direction.

I can confirm. I've been using that and it should give exactly the integral you wrote above.


> 
> Also I think (I'm not sure) it works only if the z- is perpendicular to 
> the xy-plane.

There is a variable that let's you chose the direction along which to plot the quantity 
(the other two are integrated up). Please read the header of PP/average.f90.

Cheers,

GS

> 
> With regards,
> Prasenjit.
> 
> 
> 
> -- 
> PRASENJIT GHOSH,
> POST-DOC,
> ROOM NO: 265, MAIN BUILDING,
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> ITALY
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> 
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