Well, you could start by using the unit cell instead of the simple-cubic
super-cell, unless you have some specific reason for this.
In the next version of QE there will be a generalized implementation of
exchange using localized wavefunction in real-space, although in my
experience it is not much faster than the normal algorithm when studying
such a small system.
If you are running on a large number of CPUs, activating bands
parallelization (-nbnd XX) can make it much more efficient
cheers
On 7/10/20 11:36 AM, ygxu17 wrote:
Hello Lorenzo,
Thanks for you advice. I tried nqx1=nqx2=nqx3=2 and got the value of
1.33 eV for the gamma point gap. It seems the problem comes from the
sampling mesh grid.
However, as is known, HSE calculation is expensive. In my calculation of
TiO2, 240 atoms and gamma_only kpoints are used. How should I set the
nqx for this calculation from your experience?('1 1 1' fails to
reproduce the bandgap.) By the way, is there any advice to speed up the
HSE scf calculation?
&CONTROL
title = 'TiO2'
calculation = 'scf'
restart_mode = 'from_scratch'
outdir = './1/'
pseudo_dir = './'
prefix = 'C'
tstress = .true.
tprnfor = .true.
wf_collect=.true.
disk_io = 'low'
verbosity = 'high'
/
&SYSTEM
ibrav = 0
nat = 240
ntyp = 2
ecutwfc = 90
ecutfock = 180
nosym = .true.
tot_charge = 0
!nbnd=20
occupations='smearing', smearing='gaussian', degauss=0.002
input_dft = 'hse'
nqx1 = 1
nqx2 = 1
nqx3 = 1
exx_fraction = 0.25
/
&ELECTRONS
diagonalization = 'david'
conv_thr = 1.0D-6
adaptive_thr = .true.
mixing_beta = 0.7
electron_maxstep=100
/
&IONS
ion_dynamics = 'bfgs'
/
ATOMIC_SPECIES
Ti 47.867 Ti.SG15.PBE.UPF
O 15.999 O.SG15.PBE.UPF
K_POINTS gamma
CELL_PARAMETERS bohr
22.2322500562796 0.000000000000000E+000 0.000000000000000E+000
0.000000000000000E+000 24.3827575075721 0.000000000000000E+000
0.000000000000000E+000 0.000000000000000E+000 57.4954854151373
ATOMIC_POSITIONS bohr
Ti 0.000000000000000E+000 6.09568937689302 2.41706800158272
Ti 0.000000000000000E+000 0.000000000000000E+000 7.80624023418306
Ti 0.000000000000000E+000 6.09568937689302 14.8977770162714
Ti 0.000000000000000E+000 0.000000000000000E+000 20.6787177547025
Ti 0.000000000000000E+000 6.09568937689302 27.2633365743639
Ti 2.77903125703495 0.000000000000000E+000 1.45370321265824
...
Best regards,
Greg Xu
On 7/10/2020 16:17，Lorenzo Paulatto<[email protected]>
<mailto:[email protected]> wrote：
nqx1 = 1
nqx2 = 1
nqx3 = 1
Hello Greg,
these choce of parameters is cheap, but not very well converged. Did
you
try to use a finer grid for exchange?
cheers
--
Lorenzo Paulatto - Paris
_______________________________________________
Quantum ESPRESSO is supported by MaX
(www.max-centre.eu/quantum-espresso)
users mailing list [email protected]
https://lists.quantum-espresso.org/mailman/listinfo/users
_______________________________________________
Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso)
users mailing list [email protected]
https://lists.quantum-espresso.org/mailman/listinfo/users
--
Lorenzo Paulatto - Paris
_______________________________________________
Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso)
users mailing list [email protected]
https://lists.quantum-espresso.org/mailman/listinfo/users
