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<DIV><FONT face=Arial><FONT color=#0000ff><FONT size=2><SPAN
class=671140023-25032003>Dear PWSCF
users, </SPAN></FONT></FONT></FONT></DIV>
<DIV><FONT face=Arial><FONT color=#0000ff><FONT size=2><SPAN
class=671140023-25032003></SPAN></FONT></FONT></FONT> </DIV>
<DIV><FONT><FONT><FONT face=Arial><FONT color=#0000ff><FONT size=2><SPAN
class=671140023-25032003>a couple of days ago I reported a problem with the
anomaly in the bulk Pt phonon
dispersion,</SPAN></FONT></FONT></FONT></FONT></FONT></DIV>
<DIV><FONT><FONT><FONT face=Arial><FONT color=#0000ff><FONT size=2><SPAN
class=671140023-25032003>but it was beautifully solved according to the
instruction suggested below by Stefano de
Gironcoli.</SPAN></FONT></FONT></FONT></FONT></FONT></DIV>
<DIV><FONT><FONT><FONT face=Arial><FONT color=#0000ff><FONT size=2><SPAN
class=671140023-25032003>Really I could reproduce accurately the anomaly in
the bulk Pt phonon dispersion.</SPAN></FONT></FONT></FONT></FONT></FONT></DIV>
<DIV><FONT><FONT><FONT face=Arial><FONT color=#0000ff><FONT size=2><SPAN
class=671140023-25032003> </SPAN></FONT></FONT></FONT></FONT></FONT></DIV>
<DIV><FONT><FONT><FONT face=Arial><FONT color=#0000ff><FONT size=2><SPAN
class=671140023-25032003></SPAN></FONT></FONT></FONT></FONT></FONT><FONT><FONT><FONT><FONT><FONT
face=Arial><FONT color=#0000ff><FONT size=2><SPAN class=671140023-25032003>Just
a small question: during a phonon calculation of a slab consisting several
layers, </SPAN></FONT></FONT></FONT></FONT></FONT></FONT></FONT></DIV>
<DIV><FONT><FONT><FONT><FONT><FONT face=Arial><FONT color=#0000ff><FONT
size=2><SPAN class=671140023-25032003>I'm seeing the
following messages.
</SPAN></FONT></FONT></FONT></FONT></FONT></FONT></FONT><FONT><FONT><FONT><FONT><FONT><FONT><FONT
face=Arial><FONT color=#0000ff><FONT size=2><SPAN class=671140023-25032003>Could
any of you explain why I'm getting these
messages?</SPAN></FONT></FONT></FONT></FONT></FONT></FONT></FONT></FONT></FONT></DIV>
<DIV><FONT><FONT><FONT><FONT><FONT><FONT><FONT face=Arial><FONT
color=#0000ff><FONT size=2><SPAN class=671140023-25032003>Can this be
a effect on the final result of
phonons? </SPAN></FONT></FONT></FONT></FONT></FONT></FONT></FONT></FONT></FONT></DIV>
<DIV><FONT><FONT><FONT><FONT><FONT><FONT><FONT face=Arial><FONT
color=#0000ff><FONT size=2><SPAN
class=671140023-25032003></SPAN></FONT></FONT></FONT></FONT></FONT></FONT></FONT></FONT></FONT> </DIV>
<DIV><FONT><FONT><FONT><FONT><FONT><FONT><FONT face=Arial><FONT
color=#0000ff><FONT size=2><SPAN class=671140023-25032003>(I say that most of
the parameters I'm using are
defaults.)</SPAN></FONT></FONT></FONT></FONT></FONT></FONT></FONT></FONT></FONT></DIV>
<DIV><FONT><FONT><FONT><FONT><FONT><FONT><FONT><FONT><SPAN
class=671140023-25032003></SPAN><FONT face=Arial><FONT color=#0000ff><FONT
size=2><SPAN
class=671140023-25032003>---------------------------------------------------------------------------------------------------------</SPAN> </FONT></FONT></FONT></FONT></FONT></FONT></FONT></FONT></FONT></FONT></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2> nbndx
= 56 nbnd = 55
natomwfc = 56 npwx =
696<BR> nelec = 92.00 nkb
= 121 ngl =
7557</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2>Possibly too few bands at
point 1 .00000
.00000 .00000</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2>Possibly too few bands at
point 2 .04167
.07217 .00000</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2>Possibly too few bands at
point 8 .08333
.00000 .00000</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=671140023-25032003>--------------------------------------------------------------------------------------------------------</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=671140023-25032003></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=671140023-25032003>Thanks
a lot.</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=671140023-25032003></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=671140023-25032003>Sampyo</SPAN></FONT></DIV>
<BLOCKQUOTE dir=ltr style="MARGIN-RIGHT: 0px">
<DIV></DIV>
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left><FONT
face=Tahoma size=2>-----Original Message-----<BR><B>From:</B> Stefano de
Gironcoli [mailto:degironc@sissa.it] <BR><B>Sent:</B> Friday, March 21, 2003
2:49 AM<BR><B>To:</B> pw_forum@pwscf.org<BR><B>Subject:</B> Re: [Pw_forum] Pt
bulk phonon calculated by PWSCF 1.2.0<BR><BR></FONT></DIV>Phonon anomalies in
metals are related to Fermi surface nesting. <BR>You therefore need to
describe correctly the Fermi surface. <BR>This imply looking for the limit
where degauss->0 (mantaining good convergence <BR>with respect BZ sampling)
<BR>I suggest you keep a reasonable cutoff (35 or less should be OK for
Pt) and study <BR>instead the phonon dispersion behaviour with respect
the degauss value. <BR>Proceed as follow: <BR>For each value of degauss you
should increase the k point mesh until frequencies are <BR>stable. <BR>Look
for the behavior of the converged frequency as you reduce degauss.
<P>For not anomalous frequencies things should be rather insensitive to these
details but <BR>for the anomalous ones you should see the difference.
<P>Have a look to the following two references:
<P>S. de Gironcoli, Lattice Dynamics of Metals from Density-Functional
Perturbation Theory, Phys. Rev. B 51, 6773 (1995). <BR>C. Bungaro, S. de
Gironcoli, and S. Baroni, Theory of the anomalous Rayleigh dispersion at
H/W(110) surfaces, Phys. Rev. Lett. 77, 2491 (1996).
<P>all the best
<P>stefano
<P>"Hong, SamPyo" wrote:
<BLOCKQUOTE TYPE="CITE"><!-- Converted from text/rtf format -->
<P><FONT face=Arial><FONT size=-1>Hello, dear PWSCF users</FONT></FONT>
<P><FONT face=Arial><FONT size=-1>Recently I calculated the bulk phonons of
Pt along Gamma-K direction.</FONT></FONT> <BR><FONT face=Arial><FONT
size=-1>I attached the results in pdf format, where B,C and D are the ones
calculated using PWSCF 1.2.0 version.</FONT></FONT> <BR><FONT
face=Arial><FONT size=-1>The open circles are done by a mixed-basis code.
The comparison shows that the frequencies obtained by</FONT></FONT>
<BR><FONT face=Arial><FONT size=-1>PWSCF are showing some lowering of
frequencies but oveall it's failing to reproduce the experimentally-observed
anomaly in bulk Pt dispersion</FONT></FONT>
<P><FONT face=Arial><FONT size=-1>along Gamma-K line while a mixed basis
program is doing good job.</FONT></FONT> <BR><FONT face=Arial><FONT
size=-1>I used ecut of 35 ryd for H/Pt US potentials and 72 special
k-points. I increased the ecut to 40 ryd but just very slight changes in
frequecies.</FONT></FONT>
<P><FONT face=Arial><FONT size=-1>I also tried higher cut-off for charge
density up to 10 times of ecut but just very small changes in
frequencies.</FONT></FONT>
<P><FONT face=Arial><FONT size=-1>What else can I try to get better
frequencies for bulk Pt? Could any of you give me some informations ? You
will be very appreciated.</FONT></FONT>
<P><FONT face=Arial><FONT size=-1>Sampyo</FONT></FONT>
<P><FONT face=Arial><FONT color=#000000><FONT
size=-1><<ptbulk2.pdf>></FONT></FONT></FONT></P></BLOCKQUOTE></BLOCKQUOTE></BODY></HTML>