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<div>Dear Quantum Espresso users,</div><div><br></div><div>Using QE6.5, I did an HSE scf calculation on the rutile TiO2 and found it failed to reproduce the bandgap (much smaller than the values reported or calculated with VASP code). Then I did a test of Si and checked the gaps at the gamma point. (Although silicon is an indirect bandgap semiconductor, this doesn't matter to illustrate the problem.) The result shows that the gaps at gamma point calculated with PBE and HSE functionals are 0.72eV and 0.70eV, respectively. For comparison, the calculation using VASP code shows values of 0.75eV and 1.34eV, with PBE and HSE functionals respectively.</div><div>I don't know whether I made any mistake during this calculation and I hope you can help me with this problem. The input file is attached as below. Any advice to improve the calculation is also welcomed. Thanks a lot!</div><div><br></div><div><div>&CONTROL</div><div> title = 'Si'</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 = 8</div><div> ntyp = 1</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><br></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><br></div><div> /</div><div> &ELECTRONS</div><div> diagonalization = 'david'</div><div> conv_thr = 1.0D-7</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><br></div><div>ATOMIC_SPECIES</div><div>Si 28.086 Si_ONCV_PBE_sr.upf</div></div><div><br></div><div><div>K_POINTS</div><div>10</div><div> 0.00000000000000 0.00000000000000 0.00000000000000 1</div><div> 0.25000000000000 0.00000000000000 0.00000000000000 6</div><div> 0.50000000000000 0.00000000000000 0.00000000000000 3</div><div> 0.25000000000000 0.25000000000000 0.00000000000000 12</div><div> 0.50000000000000 0.25000000000000 0.00000000000000 12</div><div> 0.50000000000000 0.50000000000000 0.00000000000000 3</div><div> 0.25000000000000 0.25000000000000 0.25000000000000 8</div><div> 0.50000000000000 0.25000000000000 0.25000000000000 12</div><div> 0.50000000000000 0.50000000000000 0.25000000000000 6</div><div> 0.50000000000000 0.50000000000000 0.50000000000000 1</div><div><br></div><div> CELL_PARAMETERS bohr</div><div> 10.3343982983998 0.000000000000000E+000 0.000000000000000E+000</div><div> 0.000000000000000E+000 10.3343982983998 0.000000000000000E+000</div><div> 0.000000000000000E+000 0.000000000000000E+000 10.3343982983998</div><div><br></div><div> ATOMIC_POSITIONS bohr</div><div> Si 0.000000000000000E+000 0.000000000000000E+000 0.000000000000000E+000</div><div> Si 0.000000000000000E+000 5.16719914919990 5.16719914919990</div><div> Si 5.16719914919990 5.16719914919990 0.000000000000000E+000</div><div> Si 5.16719914919990 0.000000000000000E+000 5.16719914919990</div><div> Si 7.75079917851337 2.58359957459995 7.75079917851337</div><div> Si 2.58359957459995 2.58359957459995 2.58359957459995</div><div> Si 2.58359957459995 7.75079917851337 7.75079917851337</div><div> Si 7.75079917851337 7.75079917851337 2.58359957459995</div></div><div><br></div><div>Best regards,</div><div>Greg Xu</div><div>Department of physics, Fudan University.</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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