[Pw_forum] visualization of the orbitals produced with the hybrid functional
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 > > 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: > > ___ > 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
[Pw_forum] visualization of the orbitals produced with the hybrid functional
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:
[Pw_forum] visualization of the orbitals produced with the hybrid functional
Dear Layla and Giuseppe, Thank you for your great comments and explanations. That clarifies the thing. Alexey - Original Message - From: "Layla Martin-Samos" To: "PWSCF Forum" Sent: Wednesday, November 7, 2012 3:19:54 AM Subject: Re: [Pw_forum] visualization of the orbitals produced with the hybrid functional 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 ___ Pw_forum mailing list Pw_forum at pwscf.org http://pwscf.org/mailman/listinfo/pw_forum -- Dr. Alexey V. Akimov Postdoctoral Research Associate Department of Chemistry University of Rochester aakimov at z.rochester.edu
[Pw_forum] visualization of the orbitals produced with the hybrid functional
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 -- Dr. Alexey V. Akimov Postdoctoral Research Associate Department of Chemistry University of Rochester aakimov at z.rochester.edu
