<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class=""><br class=""></div>If the information you have provided is correct, it seems to me that QE prints in output EXACTLY what you expect. Because you use a tetragonal lattice, the crystal units are obtained from flat units after multiplying ONLY the z<div class="">coordinate by c/a=1.55292. Therefore:</div><div class=""> 1 Ti tau( 1) = ( 0.5000000 0.5000000 0.3219736 ) -> 0.5 0.5 0.3219736*1.55292=0.5<br class=""> 2 Ti tau( 2) = ( 0.0000000 0.0000000 0.0000000 ) -> 0 0 0<br class=""> 3 O tau( 3) = ( 0.0000000 0.0000000 0.4475434 ) -> 0 0 0.4475434 0.1255697=0.695 withe 0.695=1-z that is equivalent to (0,0,-z)<br class=""> 4 O tau( 4) = ( 0.5000000 0.5000000 0.1255697 ) -> 0.5 0.5 0.1255697*1.55292=0.195=-z+1/2<br class=""> 5 O tau( 5) = ( 0.5000000 0.5000000 0.5183776 ) -> 0.5 0.5 0.5183776*1.55292=0.805=z+1/2<br class=""> 6 O tau( 6) = ( 0.0000000 0.0000000 0.1964039 ) -> 0 0 0.1964039*1.55292=z</div><div class=""><br class=""></div><div class=""><br class=""></div><div class="">On the right the positions are in crystal coordinates, and are EXACTLY those you have listed at the beginning of your message.</div><div class=""><br class=""></div><div class="">Giovanni</div><div class=""><br class=""><div><blockquote type="cite" class=""><div class="">On 01 Jul 2016, at 10:08, Muthu V <<a href="mailto:muthu.physicsmath@gmail.com" class="">muthu.physicsmath@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class=""><div class="gmail_default" style="font-family: 'comic sans ms', sans-serif;"><div class="gmail_default" style="font-family: 'comic sans ms', sans-serif;">Dear Users<br class=""></div><div class="gmail_default" style="font-family: 'comic sans ms', sans-serif;">I
have a question regarding the usage of crystal_sg option to specify
atomic position in pw input file. I'm trying make pw i/p file for TiO2
rutile system. its space group # is 136 , Ti is at 2a site and O is at 4e site.so from ITA i have the following i/p data<br class=""><div class="gmail_default" style="font-family: 'comic sans ms', sans-serif;"><br class="">Ti 2a (0, 0, 0) (0.5, 0.5, 0.5)<br class=""></div>O 4e (0, 0, z) (0.5, 0.5, z+1/2) (0.5, 0.5, -z+1/2)(0,0,-z)<br class=""><br class=""></div><div class="gmail_default" style="font-family: 'comic sans ms', sans-serif;">the z value is 0.305. so from this i have created following pw.x input file <br class=""><br class="">&control<br class=""> calculation ='scf'<br class=""> restart_mode = 'from_scratch',<br class=""> prefix = 'ge'<br class=""> pseudo_dir = '/home/pearl/qe-5.4.0/pseudo/',<br class=""> outdir ='/home/pearl/qe-5.4.0/tio2/tmp/'<br class=""> /<br class=""> &system<br class=""> ibrav = 6 ,<br class=""> space_group = 136,<br class=""> A = 4.59373 ,<br class=""> C = 2.95812 ,<br class=""> nat = 2 , <br class=""> ntyp = 2 ,<br class=""> ecutwfc = 20.0 ,<br class=""> ecutrho = 80.0 ,<br class=""> occupations = 'smearing' ,<br class=""> degauss = 0.1 ,<br class=""> smearing = 'gaussian' ,<br class=""> /<br class=""> &electrons<br class=""> conv_thr = 1.0d-8 ,<br class=""> mixing_beta = 0.7 ,<br class=""> /<br class="">ATOMIC_SPECIES<br class=""> Ti 47.867 Ti.pz-mt_fhi.UPF<br class=""> O 16.000 O.pz-mt_fhi.UPF<br class="">ATOMIC_POSITIONS crystal_sg<br class="">Ti 2a <br class="">O 4e 0.305<br class="">K_POINTS automatic<br class="">4 4 4 0 0 0<br class=""><br class=""></div><div class="gmail_default" style="font-family: 'comic sans ms', sans-serif;">with this file i'm able to run pw.x without any error message. but the following are my questions :<br class=""><br class=""></div><div class="gmail_default" style="font-family: 'comic sans ms', sans-serif;">1) the atomic position written in output file by pw.x is very different from the expected. why ?<br class=""><br class=""></div><div class="gmail_default" style="font-family: 'comic sans ms', sans-serif;">from ge.pw.out file i have ( created by pw.x for above input file)<br class="">Cartesian axes<br class=""> site n. atom positions (alat units)<br class=""> 1 Ti tau( 1) = ( 0.5000000 0.5000000 0.3219736 )<br class=""> 2 Ti tau( 2) = ( 0.0000000 0.0000000 0.0000000 )<br class=""> 3 O tau( 3) = ( 0.0000000 0.0000000 0.4475434 )<br class=""> 4 O tau( 4) = ( 0.5000000 0.5000000 0.1255697 )<br class=""> 5 O tau( 5) = ( 0.5000000 0.5000000 0.5183776 )<br class=""> 6 O tau( 6) = ( 0.0000000 0.0000000 0.1964039 )<br class=""><br class=""></div><div class="gmail_default" style="font-family: 'comic sans ms', sans-serif;">but the atomic positions are (in crystal unit )<br class=""></div><div class="gmail_default" style="font-family: 'comic sans ms', sans-serif;"> Ti 0.000000000 0.000000000 0.000000000<br class=""></div><div class="gmail_default" style="font-family: 'comic sans ms', sans-serif;"> Ti 0.500000000 0.500000000 0.500000000<br class=""></div><div class="gmail_default" style="font-family: 'comic sans ms', sans-serif;"> O 0.305299997 0.305299997 0.000000000<br class=""></div><div class="gmail_default" style="font-family: 'comic sans ms', sans-serif;"> O 0.694700003 0.694700003 0.000000000<br class=""></div><div class="gmail_default" style="font-family: 'comic sans ms', sans-serif;"> O 0.194700003 0.805299997 0.500000000<br class=""></div><div class="gmail_default" style="font-family: 'comic sans ms', sans-serif;"> O 0.805299997 0.194700003 0.500000000<br class=""><br class=""></div><div class="gmail_default" style="font-family: 'comic sans ms', sans-serif;">my second question is <br class=""><br class=""></div><div class="gmail_default" style="font-family: 'comic sans ms', sans-serif;">2) why QE is not giving correct atomic position if i use crystal_sg option ?<br class=""><br class=""></div><div class="gmail_default" style="font-family: 'comic sans ms', sans-serif;">cay anyone help me in this regard. with this mail i have enclosed the output file for the given input file<br class="">Thank you <br class=""><br class=""><b class=""><span style="color:rgb(0,0,255)" class="">================================<br class=""></span></b></div><div class="gmail_default" style="font-family:comic sans ms,sans-serif"><b class=""><span style="color:rgb(0,0,255)" class="">Muthu V<br class=""></span></b></div><div class="gmail_default" style="font-family:comic sans ms,sans-serif"><b class=""><span style="color:rgb(0,0,255)" class="">Sri Paramakalyani College<br class=""></span></b></div><div class="gmail_default" style="font-family: 'comic sans ms', sans-serif;"><b class=""><span style="color:rgb(0,0,255)" class="">Alwarkurichi<br class="">================================</span></b><br class=""></div></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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