Dear All, I have a doubt I am not able to fix by myself. I am
doing an "scf" spin polarized calculation for both the ZB and the WZ form of
ZnO, at HSE level, with the development version of PWscf. For what regard the
pseudo of Zn, I am using one with 2e only in the valence (PRB 81, 125207
(2010)). What I notice is that the DeltaE between the two systems is huge (4.4
Ry), with a macroscopic error on the bandgap of ZB-ZnO. Can this only be
ascribed to the small number of electrons in the valence? I here report the
two input files for both systems. I moreover think that the downsampling of the
Fock exchange operator (q) can not be so much influent. But maybe I am wrong
Thanks in advance for any hint you may give me.
Best,
Giacomo---------------------------------
Giacomo Giorgi
Department of Chemical System Engineering,
School of Engineering, The University of Tokyo
7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
E-mail: giacomo at tcl.t.u-tokyo.ac.jp
1) WZ-ZnO
&SYSTEM
ibrav= 4, celldm(1) =6.140475627,
celldm(3)=1.6014648858250753985351141749246, nat= 4, ntyp= 2,
ecutwfc =80.0, nbnd = 20,force_symmorphic=.true., nspin=2,
tot_magnetization=0,
input_dft='hse', nqx1 = 2, nqx2 = 2, nqx3 = 1,
x_gamma_extrapolation = .TRUE.
/
&ELECTRONS
diagonalization='david'
mixing_mode = 'plain'
mixing_beta = 0.7
conv_thr = 1.0d-8
/
ATOMIC_SPECIES
Zn 65.409 Zn_pz-2_nlcc.cpi.UPF
O 15.999 O.pz-mt.UPF
ATOMIC_POSITIONS (crystal)
Zn 0.33333 0.66667 0.00000
Zn 0.66667 0.33333 0.50000
O 0.33333 0.66667 0.38210
O 0.66667 0.33333 0.88210
K_POINTS (automatic)
8 8 6 0 0 0
for this one I get (and it seems a reasonable result, at least from the gap)
highest occupied, lowest unoccupied level (ev): 1.4320 5.2338 total
energy = -110.48522966 Ry
2) ZB-ZnO
&system
ibrav= 2, celldm(1) =8.447075169
nat= 8, ntyp= 2, force_symmorphic=.true., nspin=2, tot_magnetization=0,
ecutwfc =80., nbnd = 50,
input_dft='hse', nqx1=2, nqx2=2, nqx3=2,
x_gamma_extrapolation = .TRUE.
/
&electrons
diagonalization='david'
mixing_mode = 'plain'
mixing_beta = 0.7
conv_thr = 1.0d-8
/
ATOMIC_SPECIES
Zn 65.38 Zn_pz-2_nlcc.cpi.UPF
O 15.9994 O.pz-mt.UPF
ATOMIC_POSITIONS (crystal)
Zn 0.00000 0.00000 0.00000
Zn 0.00000 0.50000 0.50000
Zn 0.50000 0.00000 0.50000
Zn 0.50000 0.50000 0.00000
O 0.25000 0.25000 0.25000
O 0.25000 0.75000 0.75000
O 0.75000 0.75000 0.25000
O 0.75000 0.25000 0.75000
K_POINTS automatic
8 8 8 0 0 0
For this one I get (!!)
highest occupied, lowest unoccupied level (ev): 36.4937 31.9513 (!!!)
total energy = -200.32746186 Ry
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
http://www.democritos.it/pipermail/pw_forum/attachments/20120223/36a26f43/attachment.htm
