<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Dear Srijan,<div><br></div><div>First, why do you post you request within an existing thread that has nothing to do with your problem?</div><div><br></div><div>Where is the proof that the final symmetry is different from the initial one?</div><div><br></div><div>I believe that the relaxation procedure will keep the same initial symmetry since forces and stress tensor are symmetrized according to it.</div><div>I think that you should not pay attention to differences of the order of 10^-9, since there will be always some sort of numerical/roundoff errors in the calculation.</div><div><br></div><div><br></div><div>GS</div><div><br><div><div>Il giorno 14/feb/2011, alle ore 12.15, Srijan Kumar Saha ha scritto:</div><br class="Apple-interchange-newline"><blockquote type="cite"> <br> Dear QE users,<br> <br> QE is able to find the correct symmetry for the input file, added at the end of this email.<br> Here is the proof:<br> 48 Sym.Ops. (with inversion). <br><br> However, during vc-relax it breaks the symmetry.<br>
Proof goes here:<br>
0.000000000 0.000000000 0.000000000<br> 0.250189867 0.250189867 0.250189867<br> 0.000000000 0.250189689 0.250189689<br> 0.250189689 0.000000000 0.250189689<br> 0.250189689 0.250189689 0.000000000<br>
0.500379494 0.000000000 0.000000000<br> 0.750569121 0.250189867 0.250189867<br> 0.500379494 0.250189728 0.250189728<br> 0.750569299 0.000000000 0.250189689<br> 0.750569299 0.250189689 0.000000000<br>
0.000000000 0.500379494 0.000000000<br> 0.250189867 0.750569121 0.250189867<br> 0.000000000 0.750569299 0.250189689<br> 0.250189728 0.500379494 0.250189728<br> 0.250189689 0.750569299 0.000000000<br>
0.500379494 0.500379494 0.000000000<br> 0.750569121 0.750569121 0.250189867<br> 0.500379494 0.750569260 0.250189728<br> 0.750569260 0.500379494 0.250189728<br> 0.750569299 0.750569299 0.000000000<br>
0.000000000 0.000000000 0.500379494<br> 0.250189867 0.250189867 0.750569121<br> 0.000000000 0.250189689 0.750569299<br> 0.250189689 0.000000000 0.750569299<br> 0.250189728 0.250189728 0.500379494<br>
0.500379494 0.000000000 0.500379494<br> 0.750569121 0.250189867 0.750569121<br> 0.500379494 0.250189728 0.750569260<br> 0.750569299 0.000000000 0.750569299<br> 0.750569260 0.250189728 0.500379494<br>
0.000000000 0.500379494 0.500379494<br> 0.250189867 0.750569121 0.750569121<br> 0.000000000 0.750569299 0.750569299<br> 0.250189728 0.500379494 0.750569260<br> 0.250189728 0.750569260 0.500379494<br>
0.500379494 0.500379494 0.500379494<br> 0.750569121 0.750569121 0.750569121<br> 0.500379494 0.750569260 0.750569260<br> 0.750569260 0.500379494 0.750569260<br> 0.750569260 0.750569260 0.500379494<br>
<br><br> Is this possible to keep symmetry of the initial system conserved during vc-relax with BFGS ?<br> <br> Input file:<br> &control<br> calculation='vc-relax'<br> restart_mode='from_scratch',<br>
prefix='pbmno',<br> tstress = .true.<br> tprnfor = .true.<br> wf_collect=.true.<br> verbosity='high'<br> etot_conv_thr=1.0D-5, <br> forc_conv_thr=1.0D-4,<br>
/<br> &system<br> ibrav = 1,<br> nat = 40,<br> ntyp=3,<br> celldm(1)=20.70<br> nosym=.FALSE.<br> ecutwfc = 30.0,<br> ecutrho = 240.0,<br> occupations='smearing',<br> smearing='fd',<br>
degauss=0.005d0,<br> nspin=2<br> starting_magnetization(2)=1.0,<br> /<br> &electrons<br> diagonalization = 'david'<br> conv_thr = 1.0d-9<br> mixing_beta = 0.7<br> /<br> &ions<br> /<br>
&cell<br> /<br>ATOMIC_SPECIES<br> Pb 1.0 Pb.UPF<br> Mn 1.0 Mn.UPF<br> O 1.0 O.UPF<br>ATOMIC_POSITIONS (alat)<br>Pb 0.00 0.00 0.00<br>
Mn 0.25 0.25 0.25<br>O 0.00 0.25 0.25<br>O 0.25 0.00 0.25<br>O 0.25 0.25 0.00<br>Pb 0.50 0.00 0.00<br>Mn 0.75 0.25 0.25<br>O 0.50 0.25 0.25<br>
O 0.75 0.00 0.25<br>O 0.75 0.25 0.00<br>Pb 0.00 0.50 0.00<br>Mn 0.25 0.75 0.25<br>O 0.00 0.75 0.25<br>O 0.25 0.50 0.25<br>O 0.25 0.75 0.00<br>
Pb 0.50 0.50 0.00<br>Mn 0.75 0.75 0.25<br>O 0.50 0.75 0.25<br>O 0.75 0.50 0.25<br>O 0.75 0.75 0.00<br>Pb 0.00 0.00 0.50<br>Mn 0.25 0.25 0.75<br>
O 0.00 0.25 0.75<br>O 0.25 0.00 0.75<br>O 0.25 0.25 0.50<br>Pb 0.50 0.00 0.50<br>Mn 0.75 0.25 0.75<br>O 0.50 0.25 0.75<br>O 0.75 0.00 0.75<br>
O 0.75 0.25 0.50<br>Pb 0.00 0.50 0.50<br>Mn 0.25 0.75 0.75<br>O 0.00 0.75 0.75<br>O 0.25 0.50 0.75<br>O 0.25 0.75 0.50<br>Pb 0.50 0.50 0.50<br>
Mn 0.75 0.75 0.75<br>O 0.50 0.75 0.75<br>O 0.75 0.50 0.75<br>O 0.75 0.75 0.50 <br>K_POINTS {automatic}<br> 2 2 2 0 0 0<br><br>Thanking you and with my best regards,<br>Srijan K<br>
CCMT<br>Indian Institute of Science<br>India 560012<br><br>
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