Respected Sir,
Thank you for the detailed information. I will go through those papers. Regards, Ghadiyali Mohammed Kader, Research Scholar, Dept. of Physics, University of Mumbai. ________________________________ From: Thomas Brumme <[email protected]> Sent: Monday, January 8, 2018 6:26 PM To: Mohammed Ghadiyali; PWSCF Forum Subject: Re: [Pw_forum] Applying sawtooth filed parallel to a system Dear Ghadiyali Mohammed Kader, the paper by Meyer and Vanderbilt does include a discussion about the "dipole correction". The whole story (why a dipole correction is needed) is actually a little bit more involved and not so important - you just need to know, that if you want to simulate a system in an electric field, you also need to switch on the dipole correction in most cases. Irrelevant details: - Neugebauer and Scheffler wanted to simulate the adsorption of Na and K on Ag(111) (paper: Phys. Rev. B 46, 16067 (1992)) - to compensate the dipole within the system (to be able to use a 3D-periodic boundary code) they introduced an external electric field (the sawtooth potential) - Bengtsson showed that in this case it is actually not "external" but has an "internal" origin and that's why you have to multiply it by a factor of 1/2 (paper: Phys. Rev. B 59, 12301 (1999)) - the paper by Meyer and Vanderbilt is more or less a summary of these details, i.e., that for the internal dipole (also the one induced by the external field) you have a slightly different equation (the prefactor and the internal dipole needs to be recalculated each scf step as the density changes) - in VASP they actually don't cite the paper by Bengtsson but only state that a more general approach is chosen which does not include the mistake of the Neugebauer/Scheffler paper Regards Thomas On 08.01.2018 13:36, Mohammed Ghadiyali wrote: Respected Sir, Thank you for the inputs. Can you suggest any paper/s where the dipole interaction is explained? The paper by Meyer and Vanderbilt do not cover it. Regards, Ghadiyali Mohammed Kader, Research Scholar, Dept. of Physics, University of Mumbai. -- Dr. rer. nat. Thomas Brumme Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry Leipzig University Phillipp-Rosenthal-Strasse 31 04103 Leipzig Tel: +49 (0)341 97 36456 email: [email protected]<mailto:[email protected]>
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