<div dir="ltr"><div>Dear QE team,</div><div><br></div><div>Thank you for the quick replies! I recently noticed that the lowest energy orbital, which belongs to the totally symmetric irrep, does appear to be invariant to translation. Also, I can see the negative amplitudes begin to appear in translated versions of the highest occupied orbital if I break symmetry slightly (e.g. by slightly displacing an atom). <br></div><div><br></div><div>I have a couple of follow up questions:</div><div><br></div><div>1) Is there a way in QE that I can print out the contributions of each term of the Hamiltonian (kinetic energy, Kohn-Sham, local+nonlocal exchange, ...) to the energy of each individual orbital?</div><div>2) Is there a way to read the orbitals / density from the cube files back into QE to recheck the orbital energies (e.g. after possible manipulations of the orbitals)?</div><div><br></div><div>The other program, mentioned in my original post, gives energies that are quite similar to QE values, but those near the band gap differ substantially and also seem to depend on how I have translated the atoms in the preliminary QE run. If I manually translate the orbitals+atoms from the cube file output of a single QE run, then the second program gives identical energies to the untranslated orbitals. However, if I compare orbitals from two separate QE runs with different initial translations (e.g. using the inputs from my original posting), then the energies returned by the other program differ, for orbitals near the band gap. I would like to diagnose where these differences are coming from, so if there is a functionality in QE which can facilitate this task then it would be particularly helpful. Do you have any suggestions?<br></div><div><br></div><div>Kind regards,</div><div><br></div><div><div>Phillip Thomas, Ph.D.<br></div><div>National Energy Research Scientific Computing Center<br></div><div>Lawrence Berkeley National Laboratory</div></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, Aug 2, 2022 at 12:56 AM Pietro Davide Delugas <<a href="mailto:pdelugas@sissa.it" target="_blank">pdelugas@sissa.it</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
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Dear Philip </div>
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Final orbitals corresponding to degenerate set of levels may always be different sets of wavefunctions spanning the same manifold. </div>
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This may happen for a lot of reasons (e.g. a different number of MPI ranks, using a different diagonalization algorithm). </div>
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In your case the reason may be that you are running using a different set of symmetries in the 2 cases. </div>
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In supercell calculations, all symmetries that include a fractional translation are disabled. </div>
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<span style="color:rgb(0,0,0);font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt">This makes the program exclude more symmetries in the second setup ( the 3 symmetry equivalent k points in the second run are points that are symmetry equivalent
only using operations that have been excluded). </span><br>
</div>
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To avoid symmetrisation, and possibly (not warranted though) end up with the same orbitals you may use the &system flags:</div>
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nosym = .true. </div>
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or the safer </div>
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nosym_evc = .true. </div>
<div id="gmail-m_-5477680904175208193gmail-m_6506731264459013542gmail-m_-537017322751170789gmail-m_6928063564819692241appendonsend"></div>
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I hope it works, but it's not guaranteed that you will obtain the same set of orbitals even without symmetries. </div>
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<span style="color:rgb(0,0,0);font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt">best regards </span></div>
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Pietro </div>
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<div id="gmail-m_-5477680904175208193gmail-m_6506731264459013542gmail-m_-537017322751170789gmail-m_6928063564819692241divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" face="Calibri, sans-serif" color="#000000"><b>Da:</b> users <<a href="mailto:users-bounces@lists.quantum-espresso.org" target="_blank">users-bounces@lists.quantum-espresso.org</a>> per conto di Phillip Thomas <<a href="mailto:PThomas@lbl.gov" target="_blank">PThomas@lbl.gov</a>><br>
<b>Inviato:</b> martedì 2 agosto 2022 03:03<br>
<b>A:</b> <a href="mailto:users@lists.quantum-espresso.org" target="_blank">users@lists.quantum-espresso.org</a> <<a href="mailto:users@lists.quantum-espresso.org" target="_blank">users@lists.quantum-espresso.org</a>><br>
<b>Oggetto:</b> [QE-users] Translated orbitals in periodic calculation</font>
<div> </div>
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<div>Dear QE team,</div>
<div><br>
</div>
<div>I have an issue regarding orbitals generated from QE 7.0 runs on two different translated variants of a Silicon lattice. I am using a primitive cubic cell containing 8 atoms instead of the simplest 2-atom unit cell (as I need to pass the output orbitals
to another program which only accepts a tetragonal cell geometry).</div>
<div><br>
</div>
<div>Here is the input file for 'pw.x' for the first variant:</div>
<div>--------------------------------</div>
<div>&control<br>
prefix = 'silicon'<br>
calculation = 'scf'<br>
tstress = .true.<br>
etot_conv_thr = 1d-5<br>
forc_conv_thr = 1d-4<br>
/<br>
&system<br>
ibrav = 1<br>
celldm(1) = 10.173697855629921<br>
nat = 8<br>
ntyp = 1<br>
nbnd = 32<br>
ecutwfc = 80.0<br>
/<br>
&electrons<br>
electron_maxstep = 100<br>
conv_thr = 1.0d-8<br>
mixing_mode = 'plain'<br>
mixing_beta = 0.7<br>
mixing_ndim = 8<br>
diagonalization = 'david'<br>
diago_david_ndim = 4<br>
diago_full_acc = .true.<br>
/<br>
&ions<br>
/<br>
ATOMIC_SPECIES<br>
Si 28.086 Si.pw-mt_fhi.UPF<br>
ATOMIC_POSITIONS alat<br>
Si 0.00 0.00 0.00<br>
Si 0.00 0.50 0.50<br>
Si 0.50 0.00 0.50<br>
Si 0.50 0.50 0.00<br>
Si 0.25 0.25 0.25<br>
Si 0.75 0.75 0.25<br>
Si 0.25 0.75 0.75<br>
Si 0.75 0.25 0.75<br>
K_POINTS automatic<br>
4 4 4 0 0 0</div>
<div>--------------------------------</div>
<div>The second variant has the same input file except that the coordinates of the atoms are shifted to:</div>
<div><br>
</div>
<div> Si 0.125 0.125 0.125<br>
Si 0.125 0.625 0.625<br>
Si 0.625 0.125 0.625<br>
Si 0.625 0.625 0.125<br>
Si 0.375 0.375 0.375<br>
Si 0.875 0.875 0.375<br>
Si 0.375 0.875 0.875<br>
Si 0.875 0.375 0.875<br>
</div>
<div><br>
</div>
<div>Both calculations give the same total energy, -63.52598191 Ry, as I would expect, and the same band structure (except that three additional symmetry equivalent bands are printed out in the latter case); the bands for matching KPOINTS are also the same
in both runs, all as expected. Here are the bands for the 0 0 0 KPOINT for reference:<br>
</div>
<div>--------------------------------</div>
<div> End of self-consistent calculation<br>
<br>
k = 0.0000 0.0000 0.0000 ( 12797 PWs) bands (ev):<br>
<br>
-5.8606 -1.6207 -1.6207 -1.6207 -1.6207 -1.6207 -1.6207 3.3705<br>
3.3706 3.3706 3.3706 3.3706 3.3706 6.2827 6.2827 6.2827<br>
6.8712 6.8712 6.8712 6.8712 6.8712 6.8712 8.8517 8.8517<br>
8.8517 9.6765 14.0241 14.0783 14.0783 16.4618 16.4618 16.4618<br>
</div>
<div>--------------------------------</div>
<div>Now I would like to generate the orbitals for the 0 0 0 KPOINT in cube file format, so here is my input to ''pp.x':</div>
<div>--------------------------------</div>
<div> &inputpp<br>
prefix='silicon'<br>
plot_num=7<br>
kband(1)=1<br>
kband(2)= 32<br>
kpoint=1<br>
lsign=.true.<br>
/<br>
&plot<br>
iflag=3<br>
output_format=6<br>
/</div>
<div>--------------------------------</div>
<div><br>
</div>
<div>When I visually inspect the orbitals, I find that many of the orbitals are qualitatively different for the two translated variants of the lattice; they are not simply translated variants of the same orbital as I would expect. I have attached plots of the
highest occupied orbital (#16) as examples.</div>
<div><br>
</div>
<div>So I am curious, is there a mistake in my inputs or procedure that would cause differences like these? If not, then is there a way in QE that I can generate the orbitals such that they are translationally invariant? Many thanks for looking into this!</div>
<div><br>
</div>
<div>Kind regards,</div>
<div><br>
</div>
<div>Phillip Thomas, Ph.D.<br>
</div>
<div>National Energy Research Scientific Computing Center<br>
</div>
<div>Lawrence Berkeley National Laboratory<br>
</div>
</div>
</div>
</div>
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