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<DIV><FONT size=2 face=Arial>Mehmet,</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Hope you are the same person who posted a very good
tutorial on phonon calculation via</FONT></DIV>
<DIV><FONT size=2 face=Arial>small displacement method (SDM) and DFPT at Siesta
forum.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Interestingly, I noticed that in your tutorial DFPT
(PW+PH: 328 <A href="mailto:sec@8CPU">sec@8CPU</A>) was much faster
</FONT></DIV>
<DIV><FONT size=2 face=Arial>than SDM </FONT><FONT size=2
face=Arial>(Siesta+PHON: 520 <A href="mailto:sec@8CPU">sec@8CPU</A>, VASP+PHON:
1674 <A href="mailto:sec@16CPU">sec@16CPU</A>) for </FONT><FONT size=2
face=Arial>the case </FONT></DIV>
<DIV><FONT size=2 face=Arial>of graphene, at least by the criteria of
getting identical phonon dispersion relation. So, your </FONT></DIV>
<DIV><FONT size=2 face=Arial>current recommendation means that was just a
individual case for </FONT><FONT size=2 face=Arial>you, right? </FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>My feel (no </FONT><FONT size=2
face=Arial>concret numbers) with qe shows that for the previous version of qe
(before 4.0 </FONT></DIV>
<DIV><FONT size=2 face=Arial>or </FONT><FONT size=2
face=Arial>earllier?) </FONT><FONT size=2 face=Arial>PW+PH was
</FONT><FONT size=2 face=Arial>somewhat slower than PW+PHON, but the
situation is reversed </FONT></DIV>
<DIV><FONT size=2 face=Arial>with recent </FONT><FONT size=2 face=Arial>versions
of qe. </FONT> </DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>If you have further examples, please share with
us.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Thank you in advance!</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>huiqun zhou</FONT></DIV>
<DIV><FONT size=2 face=Arial>@earth sciences, nanjing university,
china</FONT></DIV>
<DIV> </DIV>
<BLOCKQUOTE
style="BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color: black"><B>From:</B>
<A title=metokal@gmail.com href="mailto:metokal@gmail.com">Mehmet Topsakal</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=pw_forum@pwscf.org
href="mailto:pw_forum@pwscf.org">PWSCF Forum</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Sunday, August 15, 2010 3:52
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [Pw_forum] Speeding up the
calculations</DIV>
<DIV><FONT size=2 face=Arial></FONT><BR></DIV>Dear Bipul,
<DIV><FONT size=2 face=Arial></FONT><BR></DIV>
<DIV>You can try Small Displacement Method ( see <A
href="http://www.homepages.ucl.ac.uk/~ucfbdxa/">http://www.homepages.ucl.ac.uk/~ucfbdxa/</A> )
which has different idea than DFPT.</DIV>
<DIV>It requires you to make 2 displacement in a supercell and calculate the
forces with single scf. You can run scf's at the same time. </DIV>
<DIV>For example, you need to calculate the forces in 5x5x1 graphene supercell
having 50 carbon atoms for 2 displacemet.</DIV>
<DIV><FONT size=2 face=Arial></FONT><FONT size=2 face=Arial></FONT><BR></DIV>
<DIV>BUT you cannot observe LO-TO splitting in polar materials (such as
honeycomb monolayer ZnO) by using SDM.</DIV>
<DIV><FONT size=2 face=Arial></FONT><FONT size=2 face=Arial></FONT><FONT
size=2 face=Arial></FONT><FONT size=2 face=Arial></FONT><BR></DIV>
<DIV>Regards.
</DIV>
<DIV><FONT size=2 face=Arial></FONT><FONT size=2 face=Arial></FONT><BR>
<DIV class=gmail_quote>On Sat, Aug 14, 2010 at 9:44 PM, Bipul Rakshit <SPAN
dir=ltr><<A
href="mailto:bipulrr@gmail.com">bipulrr@gmail.com</A>></SPAN> wrote:<BR>
<BLOCKQUOTE
style="BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8ex; PADDING-LEFT: 1ex"
class=gmail_quote>Hi PWSCF user,<BR>I am mainly doing Phonon calculation,
which generally is time consuming ( even in parallel). I just want to know
if there is any possible way to speed up the calculations. i.e. by
installing certain libraries or so. Or using some appropirate
methods<BR><BR>The machine had many nodes, and each nodes have 8/16
processors. Some of the other details of the machines are as follows:<BR><BR
clear=all> Intel(R) Xeon(R) CPU E5345 @ 2.33GHz, 64
bit<BR>4GB RAM<BR><BR>compiler: mpif90 and icc<BR><BR>Thanks<BR><FONT
color=#888888>-- <BR>Bipul Rakshit<BR>Research Fellow<BR>S N Bose Centre for
Basic Sciences,<BR>Salt Lake,<BR>Kolkata 700
098<BR>India<BR></FONT><BR>_______________________________________________<BR>Pw_forum
mailing list<BR><A
href="mailto:Pw_forum@pwscf.org">Pw_forum@pwscf.org</A><BR><A
href="http://www.democritos.it/mailman/listinfo/pw_forum"
target=_blank>http://www.democritos.it/mailman/listinfo/pw_forum</A><BR><BR></BLOCKQUOTE></DIV><BR><BR
clear=all><BR>-- <BR><BR>Mehmet Topsakal (Ph.D.
Student)<BR>UNAM-Institute of Materials Science and Nanotechnology.
<BR>Bilkent University. 06800 Bilkent, Ankara/Türkiye<BR>Tel: 0090 312 290
3527 ; Fax: 0090 312 266 4365<BR>UNAM-web : <A
href="http://www.nano.org.tr" target=_blank>www.nano.org.tr</A><BR><BR></DIV>
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