<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">As far as I understand, the LiMn2O4 has 8 formula units in one unit cell, so you definitely need 56 atoms in the unit cell.<div class=""><br class=""></div><div class="">The cif file contains only information on the inequivalent atoms, all others can be obtained from the former by applying the</div><div class="">coordinate transformation of the space group Fd-3m</div><div class=""><br class=""></div><div class="">A useful way to do that, as specified here:</div><div class=""><br class=""></div><div class=""><a href="http://www.quantum-espresso.org/faq/input-data/#3.2" class="">http://www.quantum-espresso.org/faq/input-data/#3.2</a></div><div class=""><br class=""></div><div class="">is to run the converter from cif files included in the QE distribution.</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>espresso-5.2.0/PW/tools/cif2qe.sh 1513984 > 1513984.scf.in</div><div class=""><br class=""></div><div class="">This produces a file (that you might want to check for correctness and to modify according to your needs) that looks like</div><div class=""><br class=""></div><div class=""><br class=""></div><div class="">&CONTROL<br class=""> title = '1513984'<br class=""> calculation = 'relax'<br class=""> restart_mode = 'from_scratch'<br class=""> outdir = './1'<br class=""> pseudo_dir = '../PP/atompaw'<br class=""> prefix = '1513984'<br class=""> disk_io = 'none'<br class=""> verbosity = 'default'<br class=""> etot_conv_thr = 0.0001<br class=""> forc_conv_thr = 0.001<br class=""> nstep = 400<br class=""> tstress = .true.<br class=""> tprnfor = .true.<br class=""> /<br class=""> &SYSTEM<br class=""> ibrav = 0<br class=""> nat = 56<br class=""> ntyp = 3<br class=""> ecutwfc = 60<br class=""> ecutrho = 480<br class=""> vdw_corr = 'xdm'<br class=""> xdm_a1 = 1.2153<br class=""> xdm_a2 = 2.3704<br class=""> /<br class=""> &ELECTRONS<br class=""> electron_maxstep = 200<br class=""> conv_thr = 1.0D-7<br class=""> diago_thr_init = 1e-4<br class=""> startingpot = 'atomic'<br class=""> startingwfc = 'atomic'<br class=""> mixing_mode = 'plain'<br class=""> mixing_beta = 0.5<br class=""> mixing_ndim = 8<br class=""> diagonalization = 'david'<br class=""> /<br class="">&IONS<br class=""> ion_dynamics = 'bfgs'<br class=""> /<br class=""><br class="">ATOMIC_SPECIES<br class=""> Li1+ 0.0000000000 Li1+.pw86pbe-n-kjpaw_psl.1.0.0.UPF<br class=""> Mn3.5+ 0.0000000000 Mn3.5+.pw86pbe-n-kjpaw_psl.1.0.0.UPF<br class=""> O2- 0.0000000000 O2-.pw86pbe-n-kjpaw_psl.1.0.0.UPF<br class=""><br class="">ATOMIC_POSITIONS crystal<br class="">Li1+ 0.87500000000000 0.87500000000000 0.87500000000000<br class="">Li1+ 0.12500000000000 0.12500000000000 0.12500000000000<br class="">Li1+ 0.87500000000000 0.37500000000000 0.37500000000000<br class="">Li1+ 0.37500000000000 0.87500000000000 0.37500000000000<br class="">Li1+ 0.37500000000000 0.37500000000000 0.87500000000000<br class="">Li1+ 0.12500000000000 0.62500000000000 0.62500000000000<br class="">Li1+ 0.62500000000000 0.12500000000000 0.62500000000000<br class="">Li1+ 0.62500000000000 0.62500000000000 0.12500000000000<br class="">Mn3.5+ 0.50000000000000 0.25000000000000 0.25000000000000<br class="">Mn3.5+ 0.25000000000000 0.50000000000000 0.25000000000000<br class="">Mn3.5+ 0.25000000000000 0.25000000000000 0.50000000000000<br class="">Mn3.5+ 0.50000000000000 0.50000000000000 0.50000000000000<br class="">Mn3.5+ 0.50000000000000 0.75000000000000 0.75000000000000<br class="">Mn3.5+ 0.75000000000000 0.50000000000000 0.75000000000000<br class="">Mn3.5+ 0.75000000000000 0.75000000000000 0.50000000000000<br class="">Mn3.5+ 0.00000000000000 0.25000000000000 0.75000000000000<br class="">Mn3.5+ 0.00000000000000 0.75000000000000 0.25000000000000<br class="">Mn3.5+ 0.25000000000000 0.00000000000000 0.75000000000000<br class="">Mn3.5+ 0.75000000000000 0.00000000000000 0.25000000000000<br class="">Mn3.5+ 0.25000000000000 0.75000000000000 0.00000000000000<br class="">Mn3.5+ 0.75000000000000 0.25000000000000 0.00000000000000<br class="">Mn3.5+ 0.50000000000000 0.00000000000000 0.00000000000000<br class="">Mn3.5+ 0.00000000000000 0.50000000000000 0.00000000000000<br class="">Mn3.5+ 0.00000000000000 0.00000000000000 0.50000000000000<br class="">O2- 0.73730000000000 0.01270000000000 0.01270000000000<br class="">O2- 0.01270000000000 0.73730000000000 0.01270000000000<br class="">O2- 0.01270000000000 0.01270000000000 0.73730000000000<br class="">O2- 0.73730000000000 0.73730000000000 0.73730000000000<br class="">O2- 0.26270000000000 0.98730000000000 0.98730000000000<br class="">O2- 0.98730000000000 0.26270000000000 0.98730000000000<br class="">O2- 0.98730000000000 0.98730000000000 0.26270000000000<br class="">O2- 0.26270000000000 0.26270000000000 0.26270000000000<br class="">O2- 0.73730000000000 0.51270000000000 0.51270000000000<br class="">O2- 0.23730000000000 0.01270000000000 0.51270000000000<br class="">O2- 0.23730000000000 0.51270000000000 0.01270000000000<br class="">O2- 0.01270000000000 0.23730000000000 0.51270000000000<br class="">O2- 0.51270000000000 0.73730000000000 0.51270000000000<br class="">O2- 0.51270000000000 0.23730000000000 0.01270000000000<br class="">O2- 0.01270000000000 0.51270000000000 0.23730000000000<br class="">O2- 0.51270000000000 0.01270000000000 0.23730000000000<br class="">O2- 0.51270000000000 0.51270000000000 0.73730000000000<br class="">O2- 0.73730000000000 0.23730000000000 0.23730000000000<br class="">O2- 0.23730000000000 0.73730000000000 0.23730000000000<br class="">O2- 0.23730000000000 0.23730000000000 0.73730000000000<br class="">O2- 0.26270000000000 0.48730000000000 0.48730000000000<br class="">O2- 0.76270000000000 0.98730000000000 0.48730000000000<br class="">O2- 0.76270000000000 0.48730000000000 0.98730000000000<br class="">O2- 0.98730000000000 0.76270000000000 0.48730000000000<br class="">O2- 0.48730000000000 0.26270000000000 0.48730000000000<br class="">O2- 0.48730000000000 0.76270000000000 0.98730000000000<br class="">O2- 0.98730000000000 0.48730000000000 0.76270000000000<br class="">O2- 0.48730000000000 0.98730000000000 0.76270000000000<br class="">O2- 0.48730000000000 0.48730000000000 0.26270000000000<br class="">O2- 0.26270000000000 0.76270000000000 0.76270000000000<br class="">O2- 0.76270000000000 0.26270000000000 0.76270000000000<br class="">O2- 0.76270000000000 0.76270000000000 0.26270000000000<br class=""><br class="">K_POINTS automatic<br class="">2 2 2 0 0 0<br class=""><br class="">CELL_PARAMETERS<br class=""> 15.57115429380366 0.00000000000000 0.00000000000000<br class=""> 0.00000000000000 15.57115429380366 0.00000000000000<br class=""> 0.00000000000000 0.00000000000000 15.57115429380366<br class=""><br class=""></div><div class=""><br class=""></div><div class=""><br class=""></div><div class="">Giovanni</div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><br class=""><div><blockquote type="cite" class=""><div class="">On 06 Jul 2015, at 20:51, max <<a href="mailto:aquiles011@gmail.com" class="">aquiles011@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class=""><div class=""><div class=""><div class=""><div class=""><div class="">Hello,<br class=""><br class=""></div>I'm confusing, I need to do some convergence test, but I don't know if I need primitive or one unit cell and how to select it.<br class=""><br class=""></div>I'm using this structure <a href="http://www.crystallography.net/cod/1513984.html" class="">http://www.crystallography.net/cod/1513984.html</a><br class=""><br class=""></div>I extracted the crystallographic translation. The cell formula units are 8, has 56 atoms. See ATOMIC_POSITIONS bellow.<br class=""><br class="">One unit cell of LiMn2O4 (spinel) has 7 atoms.<br class=""></div><b class=""><br class=""></b></div>I have the following questions:<b class=""><br class=""></b><div class=""><div class=""><br class=""><b class=""><b class="">Do I need to put 7 atoms in the primitive cell or how many?<br class=""><br class=""></b>How can I select the atoms position for primitive or one unit cell?</b><br class=""><br class="">ATOMIC_POSITIONS alat <br class=""> Li 0.125000000 0.125000000 0.125000000 <br class=""> Li -0.125000000 0.875000000 0.875000000 <br class=""> Li 0.875000000 -0.125000000 0.875000000 <br class=""> Li 0.875000000 0.875000000 -0.125000000 <br class=""> Li -0.125000000 -0.125000000 -0.125000000 <br class=""> Li -0.125000000 0.375000000 0.375000000 <br class=""> Li 0.375000000 0.875000000 0.375000000 <br class=""> Li 0.875000000 0.375000000 0.375000000 <br class=""> Mn 0.500000000 0.500000000 0.500000000 <br class=""> Mn -0.500000000 1.250000000 1.250000000 <br class=""> Mn 1.250000000 -0.500000000 1.250000000 <br class=""> Mn 1.250000000 1.250000000 -0.500000000 <br class=""> Mn -0.500000000 -0.500000000 -0.500000000 <br class=""> Mn 0.500000000 -0.250000000 -0.250000000 <br class=""> Mn -0.250000000 0.500000000 -0.250000000 <br class=""> Mn -0.250000000 -0.250000000 0.500000000 <br class=""> Mn -0.500000000 0.750000000 0.750000000 <br class=""> Mn 0.000000000 1.250000000 0.750000000 <br class=""> Mn 0.000000000 0.750000000 1.250000000 <br class=""> Mn 1.250000000 0.000000000 0.750000000 <br class=""> Mn 0.750000000 -0.500000000 0.750000000 <br class=""> Mn 0.750000000 0.000000000 1.250000000 <br class=""> Mn 1.250000000 0.750000000 0.000000000 <br class=""> Mn 0.750000000 1.250000000 0.000000000 <br class=""> O -0.262700000 1.012700000 1.012700000 <br class=""> O 1.012700000 -0.262700000 1.012700000 <br class=""> O 1.012700000 1.012700000 -0.262700000 <br class=""> O -0.262700000 -0.262700000 -0.262700000 <br class=""> O 0.262700000 -0.012700000 -0.012700000 <br class=""> O -0.012700000 0.262700000 -0.012700000 <br class=""> O -0.012700000 -0.012700000 0.262700000 <br class=""> O 0.262700000 0.262700000 0.262700000 <br class=""> O -0.262700000 0.512700000 0.512700000 <br class=""> O 0.237300000 1.012700000 0.512700000 <br class=""> O 0.237300000 0.512700000 1.012700000 <br class=""> O 1.012700000 0.237300000 0.512700000 <br class=""> O 0.512700000 -0.262700000 0.512700000 <br class=""> O 0.512700000 0.237300000 1.012700000 <br class=""> O 1.012700000 0.512700000 0.237300000 <br class=""> O 0.512700000 1.012700000 0.237300000 <br class=""> O 0.512700000 0.512700000 -0.262700000 <br class=""> O -0.262700000 0.237300000 0.237300000 <br class=""> O 0.237300000 -0.262700000 0.237300000 <br class=""> O 0.237300000 0.237300000 -0.262700000 <br class=""> O 0.262700000 0.487300000 0.487300000 <br class=""> O 0.762700000 -0.012700000 0.487300000 <br class=""> O 0.762700000 0.487300000 -0.012700000 <br class=""> O -0.012700000 0.762700000 0.487300000 <br class=""> O 0.487300000 0.262700000 0.487300000 <br class=""> O 0.487300000 0.762700000 -0.012700000 <br class=""> O -0.012700000 0.487300000 0.762700000 <br class=""> O 0.487300000 -0.012700000 0.762700000 <br class=""> O 0.487300000 0.487300000 0.262700000 <br class=""> O 0.262700000 0.762700000 0.762700000 <br class=""> O 0.762700000 0.262700000 0.762700000 <br class=""> O 0.762700000 0.762700000 0.262700000<br clear="all" class=""><div class=""><div class=""><div class=""><div class=""><br class="">-- <br class=""><div class="gmail_signature"><div class="">Máximo Ramírez<br class=""></div><div class="">Physics Degree<br class=""></div><div class="">Universidad Autónoma de Santo Domingo<br class=""></div></div>
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-- <br class=""><br class="">Giovanni Cantele, PhD<br class="">CNR-SPIN<br class="">c/o Dipartimento di Fisica<br class="">Universita' di Napoli "Federico II"<br class="">Complesso Universitario M. S. Angelo - Ed. 6<br class="">Via Cintia, I-80126, Napoli, Italy<br class="">e-mail: <a href="mailto:giovanni.cantele@spin.cnr.it" class="">giovanni.cantele@spin.cnr.it</a><br class="">Phone: +39 081 676910<br class="">Skype contact: giocan74<br class=""><br class="">ResearcherID: <a href="http://www.researcherid.com/rid/A-1951-2009" class="">http://www.researcherid.com/rid/A-1951-2009</a><br class="">Web page: <a href="http://people.na.infn.it/~cantele" class="">http://people.na.infn.it/~cantele</a><br class="">
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