[Pw_forum] effect of the vacum thickness on the dielectric constants

[Paolo Giannozzi]

On Sun, 2013-05-19 at 00:47 +0800, Luo Xin (IHPC) wrote:

> Dear Paolo Giannozzi,

Dear Luo Xin

if you write to the forum, you address to the forum, not to me.

The phonon code calculates the dielectric tensor and the effective
charges FOR A GIVEN SUPERCELL. For a thin film in the slab geometry,
results must be extrapolated using conventional electrostatics, I
think.

P.
> I found that in espresso-5.0.1/PHonon/PH/dielec.f90, the dielectric tensor is related with the volume of the unit cell.
> In the calculations of thin film systems, the volume of supercell will be used in DFPT, and the different vacuum thickness will affect the final dielectric tensors, does it means that after we get the dielectric tensor from the output, we should still use the exact thin film volume without vacuum to recalculate the dielectric tensor?
> Best regards !
> =======================================================
> Dr. Luo Xin
> MSE, Institute of High Performance Computing
> 1 Fusionopolis Way, #16-16, Connexis, Singapore 138632
> =======================================================
> 
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-- 
 Paolo Giannozzi, Dept. Chemistry&Physics&Environment, 
 Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
 Phone +39-0432-558216, fax +39-0432-558222