<div dir="ltr"><div><div><div>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 <br><br>J. Phys. Chem. C, <b> 119 </b>, 3060 (2015)<br><br></div>and J. Am. Chem. Soc. <b>133, </b>5893 (2011).<br><br></div>With regards,<br><br></div>Prasenjit<br></div><div class="gmail_extra"><br><div class="gmail_quote">On 8 August 2017 at 14:54, Tan Hengxin <span dir="ltr"><<a href="mailto:tanhx90@gmail.com" target="_blank">tanhx90@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Dear all,<div><br></div><div>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.</div><div>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.)</div><div>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.</div><div><br></div><div>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!</div><div><br></div><div>My input parameters for the scf run:</div><div><div>&CONTROL</div><div> calculation = 'scf',</div><div> prefix = 'ZnO',</div><div> pseudo_dir = './',</div><div>! nstep = 200,</div><div> verbosity = 'high',</div><div> wf_collect = .true.</div><div> etot_conv_thr = 1.0D-5,</div><div> forc_conv_thr = 1.0D-4,</div><div> restart_mode = 'from_scratch',</div><div> outdir = './temp_out',</div><div>/</div><div>&SYSTEM</div><div> ibrav = 0,</div><div>! celldm(1) = 1.88972688,</div><div> nat = 4,</div><div> ntyp = 2,</div><div> ecutwfc = 60,</div><div>! ecutrho = 240,</div><div>! nosym = .true.</div><div> nbnd = 36,</div><div>! occupations = 'smearing',</div><div>! degauss = 0.000367,</div><div>! smearing = 'gaussian',</div><div> input_dft = 'hse',</div><div> exx_fraction = 0.25,</div><div>! screening_parameter = 0.106</div><div>! exxdiv_treatment = gygi-baldereschi</div><div> nqx1 = 3, nqx2 = 3, nqx3 = 2,</div><div>! nspin = 2</div><div>! starting_magnetization(1) = 1.0,</div><div>! starting_magnetization(2) = -1.0,</div><div>! lda_plus_u = .true.</div><div>! hubbard_U(5) = 2.59,</div><div>! hubbard_alpha(2) = 0.d0,</div><div>! hubbard_U(2) = 3,</div><div>/</div><div>&ELECTRONS</div><div>! electron_maxstep = 100,</div><div> mixing_mode = 'plain',</div><div> mixing_beta = 0.7,</div><div> conv_thr = 1.D-8,</div><div>! startingwfc ='atomic+random',</div><div>! startingpot ='atomic',</div><div>/</div><div>&IONS</div><div> ion_dynamics = 'bfgs',</div><div> pot_extrapolation = 'atomic',</div><div> upscale = 100,</div><div> trust_radius_ini = 0.5,</div><div>/</div><div>&CELL</div><div> cell_dynamics = 'bfgs',</div><div> press_conv_thr = 0.5,</div><div> cell_dofree = 'all',</div><div>/</div><div><br></div><div>ATOMIC_SPECIES</div><div> Zn 65.38 Zn.pbe-nc.UPF</div><div> O 15.999 O.pbe-nc.UPF</div><div><br></div><div>CELL_PARAMETERS (angstrom)</div><div> 3.249 0.000 0.000</div><div> -1.625 2.814 0.000</div><div> 0.000 0.000 5.205</div><div><br></div><div>ATOMIC_POSITIONS (crystal)</div><div>Zn 0.333333343 0.666666687 0.000000000</div><div>Zn 0.666666627 0.333333313 0.500000000</div><div>O 0.333333343 0.666666687 0.382600009</div><div>O 0.666666627 0.333333313 0.882600009</div><div><br></div><div>K_POINTS {automatic}</div><div> 9 9 6 0 0 0</div></div><div><div><br></div><div>Regards,</div><div>Hengxin Tan, PhD</div><div>Department of Physics</div><div>Tsinghua University.</div><span class="HOEnZb"><font color="#888888">-- <br><div class="m_-2249406818849167048gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><pre style="color:rgb(0,0,0);line-height:16.8px;word-wrap:break-word">Tan Hengxin
Department of physics, THU.
Beijing 100084, China
Office: B403,New Science Building
E-mail:<a href="mailto:E-mail%3Athx13@mails.tsinghua.edu.cn" target="_blank">t</a><a href="mailto:anhx90@gmail.com" target="_blank">anhx90@gmail.com</a></pre></div></div></div></div></div></div></div></div>
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