Thank you all of you (Pablo, Stefano and Giuseppe) It did clarify many of my confusions.
Best Wishes, Vikas On Fri, Jul 1, 2011 at 8:30 AM, Giuseppe Mattioli <giuseppe.mattioli at mlib.ism.cnr.it> wrote: > > Dear Vikas > A final remark: > >> I am using GGA functionals >> for my relaxation. So, as you mentioned vdw-DF is improved for LDA >> type of functionals, I will stick with the london option. > > The vdW-DF functional is not a simple LDA xc functional. It contains a > long-range LDA correlation contribution. Some lines extracted from the > Modules/funct.f90 file may help to explain: > > ?! ? ? ? ? ? ? ?"pz" ? ?= "sla+pz" ? ? ? ? ? ?= Perdew-Zunger LDA > ?! ? ? ? ? ? ? ?"pbe" ? = "sla+pw+pbx+pbc" ? ?= PBE > ?! ? ? ? ? ? ? ?"revpbe"= "sla+pw+rpb+pbc" ? ?= revPBE (Zhang-Yang) > ?! ? ? ? ? ? ? ?"vdw-df"= "sla+pw+rpb+vdw" ? ?= vdW-DF > ?! > ?! Exchange: > ?! ? ? ? ? ? ? ?"sla" ? ?Slater (alpha=2/3) > ?! > ?! Correlation: "noc" ? ?none > ?! ? ? ? ? ? ? ?"pz" ? ? Perdew-Zunger > ?! ? ? ? ? ? ? ?"pw" ? ? Perdew-Wang > ?! > ?! Gradient Correction on Exchange: > ?! ? ? ? ? ? ? ?"pbx" ? ?Perdew-Burke-Ernzenhof exch > ?! ? ? ? ? ? ? ?"rpb" ? ?revised PBE by Zhang-Yang > ?! > ?! Gradient Correction on Correlation: > ?! > ?! ? ? ? ? ? ? ?"pbc" ? ?Perdew-Burke-Ernzenhof corr > ?! > ?! Van der Waals functionals > ?! ? ? ? ? ? ? ?"nonlc" ? none > ?! ? ? ? ? ? ? ?"vdw1" ? ?vdW-DF1 > ?! ? ? ? ? ? ? ?"vdw2" ? ?vdW-DF2 > ?! > ?! References: > ?! ? ? ? ? ? ? ?pz ? ? ?J.P.Perdew and A.Zunger, PRB 23, 5048 (1981) > ?! ? ? ? ? ? ? ?pbe ? ? J.P.Perdew, K.Burke, M.Ernzerhof, PRL 77, 3865 (1996) > ?! ? ? ? ? ? ? ?pw91 ? ?J.P.Perdew and Y. Wang, PRB 46, 6671 (1992) > ?! ? ? ? ? ? ? ?revPBE ?Zhang and Yang, PRL 80, 890 (1998) > ?! ? ? ? ? ? ? ?vdW-DF ?M. Dion et al., PRL 92, 246401 (2004) > ?! ? ? ? ? ? ? ? ? ? ? ?T. Thonhauser et al., PRB 76, 125112 (2007) > > Yours > Giuseppe > > On Friday 01 July 2011 09:49:54 Stefano de Gironcoli wrote: >> vdW-DF is not yet implemented in the DFPT part. >> we are working on that, >> stefano >> - >> Stefano de Gironcoli - SISSA and DEMOCRITOS >> >> On 07/01/2011 09:45 AM, Paolo Giannozzi wrote: >> > On Thu, 2011-06-30 at 12:36 -0400, Vikas Varshney wrote: >> >> Lets say for my system of interest, I want to use LDA functionals with >> >> vdw-DF setting (which will modify the wavefunctions) and run an SCF >> >> calculation on a previously relaxed geometry. Then, I do the phonon >> >> dispersion calculation (...). In that case, will the calculated >> >> dynamical matrix include the interactions from vdw forces as well? >> > >> > only in part, because you will start from vdw-aware wavefunctions, >> > but you will miss the vdw term in the second derivative of the >> > exchange-correlation functional. I just heard rumors that this >> > will be soon implemented, though >> > >> > P. >> >> _______________________________________________ >> Pw_forum mailing list >> Pw_forum at pwscf.org >> http://www.democritos.it/mailman/listinfo/pw_forum > > > > -- > ******************************************************** > - Article premier - Les hommes naissent et demeurent > libres et ?gaux en droits. Les distinctions sociales > ne peuvent ?tre fond?es que sur l'utilit? commune > - Article 2 - Le but de toute association politique > est la conservation des droits naturels et > imprescriptibles de l'homme. Ces droits sont la libert?, > la propri?t?, la s?ret? et la r?sistance ? l'oppression. > ******************************************************** > > ? ?Giuseppe Mattioli > ? ?CNR - ISTITUTO DI STRUTTURA DELLA MATERIA > ? ?v. Salaria Km 29,300 - C.P. 10 > ? ?I 00015 - Monterotondo Stazione (RM) > ? ?Tel + 39 06 90672836 - Fax +39 06 90672316 > ? ?E-mail: <giuseppe.mattioli at ism.cnr.it> > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum >
