<div dir="ltr"><div>If I remember correctly anatase has 12 atoms in a simple tetragonal unit cell. This is an example of input data I found in my disk.<br><br>Note that HGH pseudopotentials are 1) very hard: 40 Ry for wavefunctions is way too small, and 2) norm-conserving: increasing the ratio between ecutrho and ecutwfc beyond its standard value 4 is not justified,<br><br></div>Paolo<br></div><div class="gmail_extra"><br><div class="gmail_quote">On Sat, Nov 7, 2015 at 12:16 AM, Safa Alzaim <span dir="ltr"><<a href="mailto:safa.alzaim@gmail.com" target="_blank">safa.alzaim@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">Many thanks, Giovanni, for your explanation. Unfortunately, I am still getting errors. What could be the issue with the code below? I've checked all the values.<br>Thanks,<br>Safa<br><br>&CONTROL<br> title = anatase1 ,<br> calculation = 'scf' ,<br> restart_mode = 'from_scratch' ,<br> wf_collect = .true. ,<br> outdir = '/home/osboxes/qe/PWgui-5.2.1/' ,<br> wfcdir = '/home/osboxes/qe/PWgui-5.2.1/' ,<br> pseudo_dir = '/home/osboxes/qe/mypseudo/' ,<br> prefix = 'anatasetry1' ,<br> /<br> &SYSTEM<br> ibrav = 7,<br> A = 3.73 ,<br> C = 9.37 ,<br> nat = 6,<br> ntyp = 2,<br> ecutwfc = 40 ,<br> ecutrho = 320 ,<br> /<br> &ELECTRONS<br> conv_thr = 1.0d-8 ,<br> mixing_mode = 'plain' ,<br> diagonalization = 'david' ,<br> /<br>ATOMIC_SPECIES<br> Ti 46.86700 Ti.blyp-sp-hgh.UPF<br> O 15.99400 O.blyp-hgh.UPF<br>ATOMIC_POSITIONS crystal <br> Ti 0.000000000 0.000000000 0.000000000 <br> Ti 0.000000000 0.500000000 0.250000000 <br> O 0.000000000 0.000000000 0.208000000 <br> O 0.000000000 0.000000000 -0.208000000<br> O 0.000000000 0.500000000 0.458000000<br> O 0.000000000 0.500000000 0.292000000<br>K_POINTS automatic<br> 2 2 1 1 1 1 <br><div class="gmail_extra"><br><br><br><br><br><br><br><div class="gmail_quote">On Thu, Nov 5, 2015 at 9:00 AM, Giovanni Cantele <span dir="ltr"><<a href="mailto:giovanni.cantele@spin.cnr.it" target="_blank">giovanni.cantele@spin.cnr.it</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Dear Safa,<br>
<br>
the errors you get is because you input the TiO2 anatase primitive unit cell, but include also periodic replicas of some atoms, that means that as the scf cycle starts, some atoms overlap and it will never converge!<br>
<br>
For example:<br>
Ti 0.000000000 0.000000000 0.000000000<br>
and<br>
Ti 3.730000000 0.000000000 0.000000000<br>
are obtained one from the other through a lattice translation (a,0,0) and so they cannot be included both in the ATOMIC_POSITIONS card if the A and C parameters specify the crystal primitive cell.<br>
<br>
If you want to use the cif file with VESTA, before exporting the xyz coordinates you must be sure that only the atoms in the primitive cell are shown. However, you can also look through lot of papers published<br>
on TiO2 anatase and related systems. If you do so, you discover that the unit cell contains two TiO units with Ti ions at 0,0,0 and (0, 1/2 , 1/4) and O ions at (0,0,u), (0,0,-u), (0,1/2 ,u+1/4 ) and (0,1/2 , 1/2-u) with u=0.208.<br>
This coordinates are in crystal units.<br>
<br>
<br>
Giovanni<br>
<br>
--<br>
<br>
Giovanni Cantele, PhD<br>
CNR-SPIN<br>
c/o Dipartimento di Fisica<br>
Universita' di Napoli "Federico II"<br>
Complesso Universitario M. S. Angelo - Ed. 6<br>
Via Cintia, I-80126, Napoli, Italy<br>
e-mail: <a href="mailto:giovanni.cantele@spin.cnr.it" target="_blank">giovanni.cantele@spin.cnr.it</a><br>
Phone: <a href="tel:%2B39%20081%20676910" value="+39081676910" target="_blank">+39 081 676910</a><br>
Skype contact: giocan74<br>
<br>
ResearcherID: <a href="http://www.researcherid.com/rid/A-1951-2009" rel="noreferrer" target="_blank">http://www.researcherid.com/rid/A-1951-2009</a><br>
Web page: <a href="http://people.na.infn.it/~cantele" rel="noreferrer" target="_blank">http://people.na.infn.it/~cantele</a><br>
<div><div><br>
> On 05 Nov 2015, at 02:43, Safa Alzaim <<a href="mailto:safa.alzaim@gmail.com" target="_blank">safa.alzaim@gmail.com</a>> wrote:<br>
><br>
> Hello All,<br>
> I am new at QE, so please excuse the simplicity of my questions. I am working with bulk TiO2 anatase. I downloaded a cif, and then used Vesta to convert the data to xyz coordinates. However, I get the 31 atom unit cell instead of the primitive cell. In any case, I entered A and C values. I keep getting errors when I try to run the file. If anybody could help, I'd really appreciate it.<br>
> Thanks!<br>
> Safa<br>
><br>
><br>
> &CONTROL<br>
> title = anatase1 ,<br>
> calculation = 'scf' ,<br>
> restart_mode = 'from_scratch' ,<br>
> wf_collect = .true. ,<br>
> outdir = '/home/osboxes/qe/PWgui-5.2.1/' ,<br>
> wfcdir = '/home/osboxes/qe/PWgui-5.2.1/' ,<br>
> pseudo_dir = '/home/osboxes/qe/mypseudo/' ,<br>
> prefix = 'anatasetry1' ,<br>
> /<br>
> &SYSTEM<br>
> ibrav = 7,<br>
> A = 3.73 ,<br>
> C = 9.37 ,<br>
> nat = 31,<br>
> ntyp = 2,<br>
> ecutwfc = 40 ,<br>
> ecutrho = 320 ,<br>
> /<br>
> &ELECTRONS<br>
> conv_thr = 1.0d-8 ,<br>
> mixing_mode = 'plain' ,<br>
> diagonalization = 'david' ,<br>
> /<br>
> ATOMIC_SPECIES<br>
> Ti 46.86700 Ti.blyp-sp-hgh.UPF<br>
> O 15.99400 O.blyp-hgh.UPF<br>
> ATOMIC_POSITIONS angstrom<br>
> Ti 0.000000000 0.000000000 0.000000000<br>
> Ti 0.000000000 0.000000000 9.370000000<br>
> Ti 0.000000000 3.730000000 0.000000000<br>
> Ti 0.000000000 3.730000000 9.370000000<br>
> Ti 3.730000000 0.000000000 0.000000000<br>
> Ti 3.730000000 0.000000000 9.370000000<br>
> Ti 3.730000000 3.730000000 0.000000000<br>
> Ti 3.730000000 3.730000000 9.370000000<br>
> Ti 1.865000000 1.865000000 4.685000000<br>
> Ti 0.000000000 1.865000000 2.342500000<br>
> Ti 3.730000000 1.865000000 2.342500000<br>
> Ti 1.865000000 0.000000000 7.027500000<br>
> Ti 1.865000000 3.730000000 7.027500000<br>
> O 0.000000000 0.000000000 1.874000000<br>
> O 0.000000000 3.730000000 1.874000000<br>
> O 3.730000000 0.000000000 1.874000000<br>
> O 3.730000000 3.730000000 1.874000000<br>
> O 1.865000000 1.865000000 6.559000000<br>
> O 0.000000000 1.865000000 4.216500000<br>
> O 3.730000000 1.865000000 4.216500000<br>
> O 1.865000000 0.000000000 8.901500000<br>
> O 1.865000000 3.730000000 8.901500000<br>
> O 1.865000000 0.000000000 5.153500000<br>
> O 1.865000000 3.730000000 5.153500000<br>
> O 0.000000000 1.865000000 0.468500000<br>
> O 3.730000000 1.865000000 0.468500000<br>
> O 1.865000000 1.865000000 2.811000000<br>
> O 0.000000000 0.000000000 7.496000000<br>
> O 0.000000000 3.730000000 7.496000000<br>
> O 3.730000000 0.000000000 7.496000000<br>
> O 3.730000000 3.730000000 7.496000000<br>
> K_POINTS automatic<br>
> 2 2 1 1 1 1<br>
><br>
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</blockquote></div><br></div></div>
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Univ. Udine, via delle Scienze 208, 33100 Udine, Italy<br>
Phone <a href="tel:%2B39-0432-558216" value="+390432558216" target="_blank">+39-0432-558216</a>, fax <a href="tel:%2B39-0432-558222" value="+390432558222" target="_blank">+39-0432-558222</a></font></span></span></div></div></div></div>
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