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<DIV><FONT size=2 face=Arial>vicky,</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>If by node you mean a compute node with 4 or 8 CPU
cores, I'm afraid you</FONT></DIV>
<DIV><FONT size=2 face=Arial>used too much compute resource. I had ever
successfully optimized </FONT><FONT size=2 face=Arial>a spin </FONT></DIV>
<DIV><FONT size=2 face=Arial>polarized </FONT><FONT size=2 face=Arial>structure
with </FONT><FONT size=2 face=Arial>56 atoms by vc-relax</FONT> <FONT
size=2 face=Arial>on one compute node </FONT><FONT size=2 face=Arial>with 8
</FONT></DIV>
<DIV><FONT size=2 face=Arial>CPU cores within several hours. Although you didn't
mention what system </FONT></DIV>
<DIV><FONT size=2 face=Arial>you are calculating, </FONT><FONT size=2
face=Arial>I strongly recommend you try to run on one or two nodes
</FONT></DIV>
<DIV><FONT size=2 face=Arial>to see how much </FONT><FONT size=2
face=Arial>wall time it'll take.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2 face=Arial>Efficiency of parallel computing depends on many
things, one of which</FONT> <FONT size=2 face=Arial>is the</FONT></DIV>
<DIV><FONT size=2 face=Arial>system size. Usually you need to do simpler
calculations to determine how</FONT></DIV>
<DIV><FONT size=2 face=Arial>many cpu cores are optimal for your
job.</FONT> </DIV>
<DIV><FONT size=2 face=Arial></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><FONT size=2 face=Arial></FONT> </DIV>
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<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color: black"><B>From:</B>
<A title=kirtinandan07@gmail.com href="mailto:kirtinandan07@gmail.com">vicky
singh</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> Wednesday, July 21, 2010 5:50
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [Pw_forum] how does the
quantum espresso scale with increasingthe number of nodes.</DIV>
<DIV><BR></DIV>Dear prof Giannozzi<BR><BR>sorry to disturb you but i want to
ask one question. the same work raran QE simulation with 40 atoms with 8 nodes
and 12 nodes. the system got relaxed in 2 days 11 hrs with 8 nodes but it
could nod relax even in 3 days with 12 nodes. even it got relaxed with 16
nodes in 2 days 11 hrs but not relax in 6 days with 32 nodes.<BR><BR>can u
help me out.<BR><BR>with regards <BR><BR>
<DIV><BR></DIV>
<DIV class=im>
<DIV>vicky singh</DIV><FONT color=#888888>
<DIV>research student</DIV>
<DIV>Bangalore</DIV></FONT></DIV><BR><BR><BR>
<DIV class=gmail_quote>On Tue, Jul 20, 2010 at 1:17 PM, Paolo Giannozzi <SPAN
dir=ltr><<A
href="mailto:giannozz@democritos.it">giannozz@democritos.it</A>></SPAN>
wrote:<BR>
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class=gmail_quote>
<DIV class=im>vicky singh wrote:<BR><BR>> Can anybody let me know how
does the quantum espresso scale with<BR>> increasing the number of nodes
or number of processors.<BR><BR></DIV>short answer: it depends. Please read
the documentation, in<BR>particular sec.3 of the userguide; sec.5 of J.Phys.
Condens.<BR>Matter 21, 395502 (2009); the following slides:<BR><A
href="http://www.fisica.uniud.it/%7Egiannozz/QE-Tutorial/tutorial_para.pdf"
target=_blank>http://www.fisica.uniud.it/~giannozz/QE-Tutorial/tutorial_para.pdf</A><BR><BR>P.<BR><FONT
color=#888888>--<BR>Paolo Giannozzi, Democritos and University of Udine,
Italy<BR></FONT>
<DIV>
<DIV></DIV>
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