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<div>Hello Lorenzo,</div><div>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.</div><div>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?</div><div>&CONTROL
</div><div> title = 'TiO2'
</div><div> calculation = 'scf'
</div><div> restart_mode = 'from_scratch'
</div><div> outdir = './1/'
</div><div> pseudo_dir = './'
</div><div> prefix = 'C'
</div><div> tstress = .true.
</div><div> tprnfor = .true.
</div><div> wf_collect=.true.
</div><div> disk_io = 'low'
</div><div> verbosity = 'high'
</div><div> /
</div><div> &SYSTEM
</div><div> ibrav = 0
</div><div> nat = 240</div><div> ntyp = 2</div><div> ecutwfc = 90
</div><div> ecutfock = 180
</div><div> nosym = .true.
</div><div> tot_charge = 0
</div><div>!nbnd=20
</div><div>occupations='smearing', smearing='gaussian', degauss=0.002
</div><div>
</div><div> input_dft = 'hse'</div><div> nqx1 = 1
</div><div> nqx2 = 1
</div><div> nqx3 = 1
</div><div> exx_fraction = 0.25
</div><div>
</div><div> /
</div><div> &ELECTRONS
</div><div> diagonalization = 'david'
</div><div> conv_thr = 1.0D-6
</div><div> adaptive_thr = .true.
</div><div> mixing_beta = 0.7</div><div> electron_maxstep=100
</div><div> /
</div><div>&IONS
</div><div> ion_dynamics = 'bfgs'
</div><div>/
</div><div>
</div><div>ATOMIC_SPECIES
</div><div>Ti 47.867 Ti.SG15.PBE.UPF
</div><div>O 15.999 O.SG15.PBE.UPF
</div><div><br></div><div>K_POINTS gamma
</div><div><br></div><div><div> CELL_PARAMETERS bohr</div><div> 22.2322500562796 0.000000000000000E+000 0.000000000000000E+000</div><div> 0.000000000000000E+000 24.3827575075721 0.000000000000000E+000</div><div> 0.000000000000000E+000 0.000000000000000E+000 57.4954854151373</div><div><br></div><div> ATOMIC_POSITIONS bohr</div><div> Ti 0.000000000000000E+000 6.09568937689302 2.41706800158272</div><div> Ti 0.000000000000000E+000 0.000000000000000E+000 7.80624023418306</div><div> Ti 0.000000000000000E+000 6.09568937689302 14.8977770162714</div><div> Ti 0.000000000000000E+000 0.000000000000000E+000 20.6787177547025</div><div> Ti 0.000000000000000E+000 6.09568937689302 27.2633365743639</div><div> Ti 2.77903125703495 0.000000000000000E+000 1.45370321265824</div></div><div>...</div><div><br></div><div>Best regards,</div><div>Greg Xu</div><div><br></div><div id="ntes-pcmac-signature" style="font-family:'微软雅黑'"><div style="font-size:14px; padding: 0; margin:0;">
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<div style="font-size:12px;line-height:1.5;word-break:break-all;margin-left:10px;margin-right:10px">On <span class="mail-date">7/10/2020 16:17</span>，<a class="mail-to" style="text-decoration:none;color:#2a83f2;" href="mailto:paulatz@gmail.com">Lorenzo Paulatto<paulatz@gmail.com></a> wrote： </div>
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<blockquote class="mmbqc1"> nqx1 = 1<br> nqx2 = 1<br> nqx3 = 1<br></blockquote>Hello Greg,<br>these choce of parameters is cheap, but not very well converged. Did you <br>try to use a finer grid for exchange?<br><br>cheers<br><br><br>-- <br>Lorenzo Paulatto - Paris<br>_______________________________________________<br>Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso)<br>users mailing list users@lists.quantum-espresso.org<br>https://lists.quantum-espresso.org/mailman/listinfo/users</blockquote><style>
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