Dear Alexey, even in the case of Hartree-fock and occupied states is difficult to notice with the eyes a big difference. Indeed, nature is mainly mean-field and the biggest differences between standard DFT and hybrid DFT schemes are in the tail of the wave functions.
cheers Layla 2012/11/7 Giuseppe Mattioli <giuseppe.mattioli at ism.cnr.it> > > Dear Alexey > > I've plotted many HOMO and LUMO orbitals of small and large molecules by > using the HSE or the B3LYP > functional. They are often very similar to their PBE or BLYP counterparts. > This is not accountable > for an incorrect behaviour of the pp.x code. It is only the fact that, > apart from some particular > cases like those involving atomic-like d orbitals of transition metals > contained in a C-N-O-H > molecular environment, the pure DFT density is not so different from the > hybrid density. After all, > when you perform a B3LYP calculation you are only substituting about 20% > of BLYP exchange with > Hartree-Fock exact exchange... Not a great difference ;-) > > HTH > > Giuseppe > > On Tuesday 06 November 2012 18:54:00 Alexey Akimov wrote: > > Dear all, > > > > I calculated the charge density for some KS orbitals(lets say HOMO and > > LUMO) - using the pp.x program and the converged scf reslts for PBE and > > PBE0 functionals. The orbital energies obtained with the PBE0 give much > > better estimate for the band gap than those obtained with the PBE, what > is > > expected. However I also expected to see some (substantial or at least > > minor) difference of the orbitals (the spatial localization of the > > corresponding charge densities), produced by PBE vs. PBE0 functionals. > Yet > > when visualizing they look quite the same. So is this a problem of the > > pp.x (which probably only accounts for the part of the density produced > > with the "pure" part of the PBE0 functional), is this something more > > fundamental what leads to similar orbital-projected charge densities of > > the pure and hybrid functionals or is this something I missing in the > > input files? I copy my input for pp.x below. > > > > &inputpp > > prefix = 'x' > > outdir = './' > > filplot = 'tmp.dat' > > plot_num= 7 > > kpoint=1 > > kband=222 > > / > > > > &plot > > nfile = 1 > > filepp(1) = 'tmp.dat' > > weight(1) = 1.0 > > iflag = 3 > > output_format = 6 > > fileout = 'x-KS_222.cube' > > / > > > > > > > > Thank you, > > Alexey > > -- > ******************************************************** > - 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://pwscf.org/mailman/listinfo/pw_forum > -------------- next part -------------- An HTML attachment was scrubbed... URL: http://pwscf.org/pipermail/pw_forum/attachments/20121107/d60d5c8f/attachment.html
