Dear Stefan nqx in your first calc is set to 4 while it is set to 1 in the second. Only one q for forck is most probably too scarce. It might be the reason for the discrepancy.
cheers Layla 2018-05-06 17:34 GMT+02:00 Dr. Thomas Brumme <[email protected]>: > Dear Stefan, > > you can't calculate the band structure using a self-consistent calculation. > This would mean that you search for the ground-state density (scf) whilst > your integrations in k-space are done on a very sparse grid... On the other > hand you can't calculate the band structure for hybrid functionals using > an nscf or bands calculation - the answer was given recently by Lorenzo > Paulatto and I cite his answer at the end of the mail - you can find it > under the following link: > > https://www.mail-archive.com/[email protected] > g/msg33817.html > > I can furthermore add to Lorenzos answer that you can also get the band > structure by interpolating the E(k) dispersion on the regular grid like it > is done in the BoltzTraP code: > > https://www.imc.tuwien.ac.at//forschungsbereich_theoretische > _chemie/forschungsgruppen/prof_dr_gkh_madsen_ > theoretical_materials_chemistry/boltztrap/ > https://www.sciencedirect.com/science/article/pii/S0010465506001305 > > Regards > > Thomas > > > the mail: > > Hello, > The problem is quite fundamental, because in order to get the Fock > operator at a certain k-point you need the wavefunctions on a grid that is > commensurate with it, this can only be done self-consistently. > > However, there are a few things you can do. > > 1. I think you can add k-points to the scf calculation with weight zero, > this is boring (you'll have to specify he grid and the path by hand) and > very computationally expensive. > > 2. you can interpolate the Fock operator, this should be possible if it is > expressed om a basis of localized wavrfunctions. There is some development > in this direction, but I don't know if it has been implemented already by > someone. > > 3. You could interpolate the wavefunctions, from Wannier functions. This > is probably impossible in practice. > > 4. You can interpolate the Hamiltonian, passing through a Wannier basis > representation. This is possible, I have done it, and I've put an example > in the git developement branch (PP/examples/W90_open_grid_example/). But > you need to know, or learn, how to use Wannier90 (which is a useful skill > regardless), and to use the developement version of qe. > > Zitat von Stefan Seidl <[email protected]>: > > > Dear All, >> I am calculating with QUANTUM ESPRESSO the BANDSTRUCTURE of Silicon with >> HYBRID FUNCTIONAL HSE. >> >> My calculation contains 3 steps: >> >> 1: pw.x < si.scf.in > si.scf.out >> 2: pw.x < si.scf_instead_bands.in > >> si.scf_instead_bands.out >> 3: bands.x < bands.in > bands.out >> >> to 1: I am using an explicit kpoint list with a correspoinding qpoint grid >> all kpoints (12 12 12 mesh )are equal weighted with 1 (which >> provides the weight 2/(12**3) ) >> ####################################################### >> &control >> calculation = 'scf' >> prefix = 'silicon', >> pseudo_dir = './', >> outdir = './calculation' >> verbosity = 'high', >> / >> &system >> ibrav = 2, >> celldm(1) = 10.2612, >> nat = 2, >> ntyp = 1, >> ecutwfc = 40.0, >> ! nbnd = 8, >> input_dft ='hse', >> nqx1 = 4, >> nqx2 = 4, >> nqx3 = 4, >> occupations = 'smearing', >> smearing = 'gaussian', >> degauss = 0.001, >> >> nosym = .TRUE., >> noinv = .TRUE., >> / >> &electrons >> mixing_beta = 0.7 >> / >> >> ATOMIC_SPECIES >> Si 28.0855 Si_NCv0.4_PBE_stringent.upf >> ATOMIC_POSITIONS >> Si 0.00 0.00 0.00 >> Si 0.25 0.25 0.25 >> K_POINTS tpiba >> 1728 >> 0.0000000 0.0000000 0.0000000 1 >> -0.0833333 0.0833333 -0.0833333 1 >> -0.1666667 0.1666667 -0.1666667 1 >> -0.2500000 0.2500000 -0.2500000 1 >> -0.3333333 0.3333333 -0.3333333 1 >> -0.4166667 0.4166667 -0.4166667 1 >> 0.5000000 -0.5000000 0.5000000 1 >> 0.4166667 -0.4166667 0.4166667 1 >> 0.3333333 -0.3333333 0.3333333 1 >> 0.2500000 -0.2500000 0.2500000 1 >> 0.1666667 -0.1666667 0.1666667 1 >> 0.0833333 -0.0833333 0.0833333 1 >> 0.0833333 0.0833333 0.0833333 1 >> 0.0000000 0.1666667 0.0000000 1 >> -0.0833333 0.2500000 -0.0833333 1 >> -0.1666667 0.3333333 -0.1666667 1 >> ... >> >> >> >> >> to 2: here I am just specifying the special kpoint path >> ####################################################### >> >> &control >> calculation = 'scf' >> prefix = 'silicon', >> pseudo_dir = './', >> outdir = './calculation' >> verbosity = 'high', >> / >> &system >> ibrav = 2, >> celldm(1) = 10.2612, >> nat = 2, >> ntyp = 1, >> ecutwfc = 40.0, >> nbnd = 8, >> input_dft ='hse', >> nqx1 = 1, >> nqx2 = 1, >> nqx3 = 1, >> occupations = 'smearing', >> smearing = 'gaussian', >> degauss = 0.001, >> >> nosym = .TRUE., >> noinv = .TRUE., >> / >> &electrons >> mixing_beta = 0.7 >> / >> >> ATOMIC_SPECIES >> Si 28.0855 Si_NCv0.4_PBE_stringent.upf >> ATOMIC_POSITIONS >> Si 0.00 0.00 0.00 >> Si 0.25 0.25 0.25 >> K_POINTS tpiba >> 50 >> 0.50000000 0.50000000 0.50000000 1 >> 0.44444444 0.44444444 0.44444444 2 >> 0.38888889 0.38888889 0.38888889 3 >> 0.33333333 0.33333333 0.33333333 4 >> 0.27777778 0.27777778 0.27777778 5 >> 0.22222222 0.22222222 0.22222222 6 >> 0.16666667 0.16666667 0.16666667 7 >> 0.11111111 0.11111111 0.11111111 8 >> 0.05555556 0.05555556 0.05555556 9 >> 0.00000000 0.00000000 0.00000000 10 >> 0.00000000 0.00000000 0.00000000 11 >> ... >> >> >> >> The eigenvalues from my 1st calculation si.scf.out are correct ! >> But the eigenvalues of the 2nd calculation si.bands.out are wrong ! >> E.g. the HOMO-LUMO distance at the Gamma point is just too big (compared >> to VASP results which are proven to be right)! >> >> Where is the mistake in my input file si.bands.in for the 2nd >> calculation ?? >> >> Thanks a lot, best >> Stefan >> > > -- > 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] > > _______________________________________________ > users mailing list > [email protected] > https://lists.quantum-espresso.org/mailman/listinfo/users >
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