[Pw_forum] How to get the usual ~2.4 eV band gap of ZnO with HSE06?
Prasenjit Ghosh
prasenjit.jnc at gmail.com
Fri Aug 11 14:46:47 CEST 2017
Since the hybrid functionals are non ab initio, you can play around with
the % of EXX to see how that affects the band gap (assuming everything else
is fine). Or else you can use GGA+U with U on both Zn and O to correct the
band gap as has been shown in the following paper
J. Phys. Chem. C, * 119 *, 3060 (2015)
and J. Am. Chem. Soc. *133, *5893 (2011).
With regards,
Prasenjit
On 8 August 2017 at 14:54, Tan Hengxin <tanhx90 at gmail.com> wrote:
> Dear all,
>
> I am doing some calculations on the HSE06 (25% EXX) band gap of wurtzite
> ZnO with experimental structure, and find that I cannot get the usual value
> of ~2.4 eV. My value is just ~2.1 eV.
> Maybe my norm-conserving pseudopotentials (NC-PPs) of Zn and O are not
> very good. So I also tried the NC-PPs for Zn and O from the
> pslibrary.0.3.1. However, the gap is even smaller (~1.8 eV). (All PPs are
> based on PBE xc.)
> I have also done different tests with different parameters, containing
> nbnd, nqx1, nqx2, nqx3, k-mesh. But I still cannot get 2.4 eV for the HSE
> gap.
>
> So could anyone provide a guidance on how to obtain the usual HSE band gap
> of 2.4 eV for wurtzite ZnO ? The input parameters are as follows, and the
> output file calculated with the NC-PPs from the pslibrary.0.3.1 is also
> attached. Thank you in advance!
>
> My input parameters for the scf run:
> &CONTROL
> calculation = 'scf',
> prefix = 'ZnO',
> pseudo_dir = './',
> ! nstep = 200,
> verbosity = 'high',
> wf_collect = .true.
> etot_conv_thr = 1.0D-5,
> forc_conv_thr = 1.0D-4,
> restart_mode = 'from_scratch',
> outdir = './temp_out',
> /
> &SYSTEM
> ibrav = 0,
> ! celldm(1) = 1.88972688,
> nat = 4,
> ntyp = 2,
> ecutwfc = 60,
> ! ecutrho = 240,
> ! nosym = .true.
> nbnd = 36,
> ! occupations = 'smearing',
> ! degauss = 0.000367,
> ! smearing = 'gaussian',
> input_dft = 'hse',
> exx_fraction = 0.25,
> ! screening_parameter = 0.106
> ! exxdiv_treatment = gygi-baldereschi
> nqx1 = 3, nqx2 = 3, nqx3 = 2,
> ! nspin = 2
> ! starting_magnetization(1) = 1.0,
> ! starting_magnetization(2) = -1.0,
> ! lda_plus_u = .true.
> ! hubbard_U(5) = 2.59,
> ! hubbard_alpha(2) = 0.d0,
> ! hubbard_U(2) = 3,
> /
> &ELECTRONS
> ! electron_maxstep = 100,
> mixing_mode = 'plain',
> mixing_beta = 0.7,
> conv_thr = 1.D-8,
> ! startingwfc ='atomic+random',
> ! startingpot ='atomic',
> /
> &IONS
> ion_dynamics = 'bfgs',
> pot_extrapolation = 'atomic',
> upscale = 100,
> trust_radius_ini = 0.5,
> /
> &CELL
> cell_dynamics = 'bfgs',
> press_conv_thr = 0.5,
> cell_dofree = 'all',
> /
>
> ATOMIC_SPECIES
> Zn 65.38 Zn.pbe-nc.UPF
> O 15.999 O.pbe-nc.UPF
>
> CELL_PARAMETERS (angstrom)
> 3.249 0.000 0.000
> -1.625 2.814 0.000
> 0.000 0.000 5.205
>
> ATOMIC_POSITIONS (crystal)
> Zn 0.333333343 0.666666687 0.000000000
> Zn 0.666666627 0.333333313 0.500000000
> O 0.333333343 0.666666687 0.382600009
> O 0.666666627 0.333333313 0.882600009
>
> K_POINTS {automatic}
> 9 9 6 0 0 0
>
> Regards,
> Hengxin Tan, PhD
> Department of Physics
> Tsinghua University.
> --
>
> Tan Hengxin
> Department of physics, THU.
> Beijing 100084, China
> Office: B403,New Science Building
> E-mail:t <E-mail%3Athx13 at mails.tsinghua.edu.cn>anhx90 at gmail.com
>
>
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--
PRASENJIT GHOSH,
IISER Pune,
Dr. Homi Bhabha Road, Pashan
Pune, Maharashtra 411008, India
Phone: +91 (20) 2590 8203
Fax: +91 (20) 2589 9790
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