On Fri, Apr 29, 2011 at 3:49 AM, Stefano de Gironcoli <degironc at sissa.it> wrote: > Dear all, > > ? ? I inquired Timo Thonhauser (now Wake Forest ?University), the main > character behind the vdW-DF functional implementation in Quantum > ESPRESSO, ?about the issue of the spin-polarized version of vdW-DF. > > I'm reporting his opinion below: > > "In general, at the moment there exists NO true extension of vdW-DF for > spin-polarized cases. Several groups have expressed interest in working > on it, but nothing has been published yet. Note that just evaluating > vdW-DF for the two spin densities separately, while simple to implement, > is an approximation which is difficult to justify: there is no > quantitative measure of the error being made, other than hand waving > arguments that it has to be small. Also, we did not implement that > simple fix, because we were afraid that people would use it as a > black-box for spin-polarized calculations, not knowing that there is no > spin-polarized vdW-DF" > > hope this helps to clarify the situation. > > stefano
Thank you Stefano and Thonhauser Timo for the clarification. -------------------------------------------------- Duy Le PhD Student Department of Physics University of Central Florida. "Men don't need hand to do things" > > > > On 04/27/2011 04:45 PM, Duy Le wrote: >> -------------------------------------------------- >> Duy Le >> PhD Student >> Department of Physics >> University of Central Florida. >> >> "Men don't need hand to do things" >> >> >> >> On Wed, Apr 27, 2011 at 3:29 AM, Stefano de Gironcoli<degironc at sissa.it> >> ?wrote: >>> the vdW energy depends on the local polarizability of the electron gas .. >>> does it depend on the spin density ? I would say so. >> I would depend as we expected, however, from the formalism of vdW-DF, >> spin is not taken into account. So, I think in the limit of vdW-DF, >> the spin-dependence is ignored. >> >>> Is it taken into account in the current definition of vdw-DF ? I would say >>> no... >>> how is it implemented in GPAW ? just blindly or with some argument ? >> I am not sure. Did not have a chance to look at it and there is no >> found document about this. >> >>> stefano >>> >>> On 04/27/2011 06:35 AM, WANG Wei wrote: >>> >>> Thank you for your advice, Deu. Yes, the non-local energy is independent the >>> spin density. >>> >>> >>> On 27 April 2011 12:34, Duy Le<ttduyle at gmail.com> ?wrote: >>> >>> -------------------------------------------------- >>> Duy Le >>> PhD Student >>> Department of Physics >>> University of Central Florida. >>> >>> "Men don't need hand to do things" >>> >>> >>> >>> On Tue, Apr 26, 2011 at 1:00 PM, Stefano de Gironcoli<degironc at sissa.it> >>> wrote: >>> >>> Dear ?WANG Wei >>> ? ?the vdw-DF functional form is not defined for spin polarized system... >>> >>> Or it does mean that non-local energy is not spin-dependent but >>> charge-density-dependent only. >>> >>> ? ?if you define, implement and test it, you could even get a nice >>> publication out of it. thank you. >>> >>> The spin-polarized vdW-DF has been implemented in GPAW. >>> >>> stefano >>> >>> >>> >>> _______________________________________________ >>> Pw_forum mailing list >>> Pw_forum at pwscf.org >>> http://www.democritos.it/mailman/listinfo/pw_forum >>> >>> >>> _______________________________________________ >>> Pw_forum mailing list >>> Pw_forum at pwscf.org >>> http://www.democritos.it/mailman/listinfo/pw_forum >>> >>> >> _______________________________________________ >> Pw_forum mailing list >> Pw_forum at pwscf.org >> http://www.democritos.it/mailman/listinfo/pw_forum > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum >
