<div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On Thu, May 26, 2016 at 12:43 AM, Qihang Liu <span dir="ltr"><<a href="mailto:qihang.liu85@gmail.com" target="_blank">qihang.liu85@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"><br><div>if one forces the use_all_frac to be true he will get a imperfect non-symmophic operation, the result is some of the representation of a certain band cannot be defined, indicated with a "?".</div></div></blockquote><div><br></div><div>well, it's not the symmetry operation that is imperfect: it is the algorithm that finds the representations that is imperfect, in my opinion. Symmetries exist in nature, FFT grids exist only in computer codes.<br><br></div><div>Paolo<br></div><div> <br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div> So the better way is to change nr1-nr3 to even numbers so that the code will not have any trouble on non-symmophic operations and provide the group representations you want. </div><div><br></div><div>If there is anything wrong please correct me. Thanks.</div><div><br></div><div>Best,</div></div><div class="gmail_extra"><br clear="all"><div><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><span style="font-size:12.8000001907349px"><br></span></div><div dir="ltr"><span style="font-size:12.8000001907349px">Qihang Liu</span><div style="font-size:12.8000001907349px"><br>Research Associate<br>Renewable and Sustainable Energy Institute (RASEI) <br>University of Colorado Boulder<br>Boulder, CO 80309-029 USA</div><div><a href="https://www.colorado.edu/zunger-materials-by-design/qihang-liu" target="_blank">https://www.colorado.edu/zunger-materials-by-design/qihang-liu</a><br></div></div></div></div></div></div></div></div></div></div>
<br><div class="gmail_quote">On Wed, May 25, 2016 at 2:29 PM, Paolo Giannozzi <span dir="ltr"><<a href="mailto:p.giannozzi@gmail.com" target="_blank">p.giannozzi@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"><div>This is what I get with your input:<br><br> 12 Sym. Ops., with inversion, found<br> (note: 12 additional sym.ops. were found but ignored<br> their fractional translations are incommensurate with FFT grid)<br><br>while with option "use_all_frac=.true.", or by setting the FFT grid to nr1=50, nr2=50, nr3=80:<br><br> 24 Sym. Ops., with inversion, found (12 have fractional translation)<br><br></div>Paolo<br></div><div class="gmail_extra"><br><div class="gmail_quote"><div><div>On Wed, May 25, 2016 at 8:36 PM, Qihang Liu <span dir="ltr"><<a href="mailto:qihang.liu85@gmail.com" target="_blank">qihang.liu85@gmail.com</a>></span> wrote:<br></div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div><div dir="ltr">Dear all,<div><br></div><div>I am struggling with the band symmetry analysis on a structure with a space group #194 P63/mmc (D_6h^4). I use the tag space_group to define it so I suppose the space group can be realized correctly by pwscf. As we know, the little group of Gamma point should follow the group of the crystal structure which is also D_6h. The the output of QE is D_3d. Please see the following input and outputs:</div><div><br></div><div><a href="http://scf.in" target="_blank">scf.in</a></div><div> &control</div><div> prefix='bulk',</div><div> pseudo_dir='./'</div><div> outdir = './',</div><div> wf_collect = .true.,</div><div> /</div><div> &system</div><div> ibrav= 4,</div><div> celldm(1)= 8.568018, celldm(3)= 1.660013, space_group = 194</div><div> nat= 3, ntyp= 3, nbnd = 48,</div><div> ecutwfc = 36.0, ecutrho = 320.0,</div><div> lspinorb = .true., noncolin = .true.,</div><div> occupations='smearing', smearing='gaussian', degauss=0.02,</div><div> /</div><div> &electrons</div><div> diagonalization='david',</div><div> conv_thr = 1.0e-8,</div><div> mixing_beta = 0.7,</div><div> /</div><div>ATOMIC_SPECIES</div><div> Li 6.941 Li.rel-pbe-s-kjpaw_psl.0.2.1.UPF</div><div> Hg 200.5 Hg.rel-pbe-dn-kjpaw_psl.0.2.2.UPF</div><div> As 74.922 As.rel-pbe-n-kjpaw_psl.0.2.UPF</div><div>ATOMIC_POSITIONS crystal_sg</div><div>Li 0.0000000000000000 0.0000000000000000 0.0000000000000000</div><div>Hg 0.3333333300000021 0.6666666699999979 0.2500000000000000</div><div>As 0.6666666699999979 0.3333333300000021 0.2500000000000000</div><div>K_POINTS automatic</div><div> 9 9 6 0 0 0 </div><div><br></div><div><a href="http://nscf.in" target="_blank">nscf.in</a></div><div><div> &control</div><div> calculation = 'nscf'</div><div> prefix='bulk',</div><div> pseudo_dir='./'</div><div> outdir = './',</div><div> wf_collect = .true.,</div><div> /</div><div> &system</div><div> ibrav= 4,</div><div> celldm(1)= 8.568018, celldm(3)= 1.660013, space_group = 194</div><div> nat= 3, ntyp= 3, nbnd = 48,</div><div> ecutwfc = 36.0, ecutrho = 320.0,</div><div> lspinorb = .true., noncolin = .true.,</div><div> occupations='smearing', smearing='gaussian', degauss=0.02,</div><div> /</div><div> &electrons</div><div> diagonalization='david',</div><div> conv_thr = 1.0e-8,</div><div> mixing_beta = 0.7,</div><div> /</div><div>ATOMIC_SPECIES</div><div> Li 6.941 Li.rel-pbe-s-kjpaw_psl.0.2.1.UPF</div><div> Hg 200.5 Hg.rel-pbe-dn-kjpaw_psl.0.2.2.UPF</div><div> As 74.922 As.rel-pbe-n-kjpaw_psl.0.2.UPF</div><div>ATOMIC_POSITIONS crystal_sg</div><div>Li 0.0000000000000000 0.0000000000000000 0.0000000000000000</div><div>Hg 0.3333333300000021 0.6666666699999979 0.2500000000000000</div><div>As 0.6666666699999979 0.3333333300000021 0.2500000000000000</div><div>K_POINTS crystal_b</div><div> 3</div><div> 0 0 0 30 ! Gamma</div><div> 0 0 0.5 30 ! A</div><div> 0.5 0 0.5 1 ! L</div><div><br></div><div><a href="http://bands.in" target="_blank">bands.in</a></div><div><div> &bands</div><div> prefix = 'bulk',</div><div> outdir='./',</div><div> filband = 'bands.dat',</div><div> lsym = .true.,</div><div> /</div></div><div><br></div><div>Output: </div><div><div> **************************************************************************</div><div><br></div><div> xk=( 0.00000, 0.00000, 0.00000 )</div><div><br></div><div> double point group D_3d (-3m)</div><div> there are 12 classes and 6 irreducible representations</div><div> the character table:</div><div><br></div><div> E -E 2C3 -2C3 3C2' -3C2' i -i 2S6 -2S6 3s_v -3s_v</div><div><br></div><div>G_4+ 2.00 -2.00 1.00 -1.00 0.00 0.00 2.00 -2.00 1.00 -1.00 0.00 0.00</div><div>G_5+ 1.00 -1.00 -1.00 1.00 0.00 0.00 1.00 -1.00 -1.00 1.00 0.00 0.00</div><div>G_6+ 1.00 -1.00 -1.00 1.00 0.00 0.00 1.00 -1.00 -1.00 1.00 0.00 0.00</div><div>G_4- 2.00 -2.00 1.00 -1.00 0.00 0.00 -2.00 2.00 -1.00 1.00 0.00 0.00</div><div>G_5- 1.00 -1.00 -1.00 1.00 0.00 0.00 -1.00 1.00 1.00 -1.00 0.00 0.00</div><div>G_6- 1.00 -1.00 -1.00 1.00 0.00 0.00 -1.00 1.00 1.00 -1.00 0.00 0.00</div></div><div><br></div><div>Can anyone help me to explain the inconsistency? Is is related to some non-symmophic symmetries that QE can not deal with? Thanks a lot.</div><div><br></div><div>Best,<br clear="all"><div><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><span style="font-size:12.8000001907349px"><br></span></div><div dir="ltr"><span style="font-size:12.8000001907349px">Qihang Liu</span><div style="font-size:12.8000001907349px"><br>Research Associate<br>Renewable and Sustainable Energy Institute (RASEI) <br>University of Colorado Boulder<br>Boulder, CO 80309-029 USA</div><div><a href="https://www.colorado.edu/zunger-materials-by-design/qihang-liu" target="_blank">https://www.colorado.edu/zunger-materials-by-design/qihang-liu</a><br></div></div></div></div></div></div></div></div></div></div>
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