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<DIV style="FONT-SIZE: 12pt; FONT-FAMILY: 'Calibri'; COLOR: #000000">
<DIV>Dear Pascal</DIV>
<DIV> </DIV>
<DIV>Please, have a look to these couple of papers:</DIV>
<DIV> </DIV>
<DIV><A title=http://dx.doi.org/10.1088/0953-8984/24/20/205503
href="http://dx.doi.org/10.1088/0953-8984/24/20/205503">http://dx.doi.org/10.1088/0953-8984/24/20/205503</A></DIV>
<DIV><A title=http://dx.doi.org/10.1016/j.cpc.2013.02.020
style="WORD-WRAP: break-word; TEXT-ALIGN: justify"
href="http://dx.doi.org/10.1016/j.cpc.2013.02.020">http://dx.doi.org/10.1016/j.cpc.2013.02.020</A></DIV>
<DIV> </DIV>
<DIV>They point to that Tran-Blaha modification to the Becke-Johnson metaGGA
functional may yield quite good bandgaps for insulators (comparable to hybrid
functionals) at a much reduced computational cost. The price to pay is that
convergence is so tricky, even for simple binary compounds. I am giving them a
chance to see if they deserve to be used instead of hybrid functionals. </DIV>
<DIV> </DIV>
<DIV>Thanks for your comments</DIV>
<DIV> </DIV>
<DIV>Juanjo</DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV
style="FONT-SIZE: small; FONT-FAMILY: 'Calibri'; FONT-WEIGHT: normal; COLOR: #000000; FONT-STYLE: normal; TEXT-DECORATION: none; DISPLAY: inline">
<DIV style="FONT: 10pt tahoma">
<DIV><FONT size=3 face=Calibri></FONT> </DIV>
<DIV style="BACKGROUND: #f5f5f5">
<DIV style="font-color: black"><B>From:</B> <A title=pascal.boulet@univ-amu.fr
href="mailto:pascal.boulet@univ-amu.fr">Pascal BOULET</A> </DIV>
<DIV><B>Sent:</B> Friday, October 31, 2014 3:17 PM</DIV>
<DIV><B>To:</B> <A title=pw_forum@pwscf.org
href="mailto:pw_forum@pwscf.org">PWSCF Forum</A> </DIV>
<DIV><B>Subject:</B> Re: [Pw_forum] TB09 metaGGA</DIV></DIV></DIV>
<DIV> </DIV></DIV>
<DIV
style="FONT-SIZE: small; FONT-FAMILY: 'Calibri'; FONT-WEIGHT: normal; COLOR: #000000; FONT-STYLE: normal; TEXT-DECORATION: none; DISPLAY: inline">
<DIV>
<DIV style="FONT-SIZE: 13px; FONT-FAMILY: georgia; COLOR: #000000">Dear
Juanjo,<BR><BR>As far as I know, metaGGAs are like GGAs for gaps: there are not
accurate. For getting good gaps you have to switch to hybrid functionals or GW
formalism (not implemented in QE though). Depending on what you want to do, of
course, and if you know the gap value you may try this: optimize with a standard
GGA functional, run a nscf calculation and if the gap is not totally closed up
then operate a rigid band shifting for further properties calculations. This is
a bit brute force...<BR><BR>If you do not know the gap value: run a hybrid
single point calculation on the GGA optimized structure.<BR><BR>As Yves said,
there are not so many options...<BR><BR>Pascal<BR><BR><BR>
<DIV
style="WORD-WRAP: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space"
dir=ltr>"Juanjo Meléndez" <melendez@unex.es> wrote:
<BLOCKQUOTE cite="<416A1BAAEB7E458788C55A933E8C9BCA@Otello>" type="cite">
<DIV dir=ltr>
<DIV style="FONT-SIZE: 12pt; FONT-FAMILY: 'Calibri'; COLOR: #000000">
<DIV>Dear Yves</DIV>
<DIV> </DIV>
<DIV>Thanks a lot for your comments. Unfortunately, I need a good description
of gaps to calculate optical absorption, and hybrid functionals are
prohibitive for the supercells that I need to use. That is why I started to
try with metaGGA.</DIV>
<DIV> </DIV>
<DIV>I will have a look to the paper you mention (which I did not know, by the
way, thanks!) for more ideas...</DIV>
<DIV> </DIV>
<DIV>Take care</DIV>
<DIV> </DIV>
<DIV>Juanjo</DIV>
<DIV
style="FONT-SIZE: small; FONT-FAMILY: 'Calibri'; FONT-WEIGHT: normal; COLOR: #000000; FONT-STYLE: normal; TEXT-DECORATION: none; DISPLAY: inline">
<DIV style="FONT: 10pt tahoma">
<DIV><FONT size=3 face=Calibri></FONT> </DIV>
<DIV style="BACKGROUND: #f5f5f5">
<DIV style="font-color: black"><B>From:</B> <A title=yves.ferro@univ-amu.fr
href="mailto:yves.ferro@univ-amu.fr">Yves Ferro</A> </DIV>
<DIV><B>Sent:</B> Friday, October 31, 2014 10:20 AM</DIV>
<DIV><B>To:</B> <A title=pw_forum@pwscf.org
href="mailto:pw_forum@pwscf.org">PWSCF Forum</A> </DIV>
<DIV><B>Subject:</B> Re: [Pw_forum] TB09 metaGGA</DIV></DIV></DIV>
<DIV> </DIV></DIV>
<DIV
style="FONT-SIZE: small; FONT-FAMILY: 'Calibri'; FONT-WEIGHT: normal; COLOR: #000000; FONT-STYLE: normal; TEXT-DECORATION: none; DISPLAY: inline">Dear
Juanjo,
<DIV> </DIV>
<DIV>From what I can remember:</DIV>
<DIV>- t<SPAN class=Apple-style-span
style="FONT-SIZE: 13px; FONT-FAMILY: georgia">he meta-GGA kinetic terms are
not saved in order to restart a nscf, at least up to the 5.0
version,</SPAN></DIV>
<DIV><FONT class=Apple-style-span face=georgia><SPAN class=Apple-style-span
style="FONT-SIZE: 13px">- the tools for building meta-GGA PPs are not
available in QE.</SPAN></FONT></DIV>
<DIV><FONT class=Apple-style-span face=georgia><SPAN class=Apple-style-span
style="FONT-SIZE: 13px">However, I'm not sure using meta-GGA pseudos will
solve your problem. Meta-GGA are known to have numerical instabilities such as
the ones you met, in particular when then electronic density drop to a very
low level as probably in your ionic crystal LiF, on the contrary with Si and C
that form covalent structures.</SPAN></FONT></DIV>
<DIV><FONT class=Apple-style-span face=georgia><SPAN class=Apple-style-span
style="FONT-SIZE: 13px"><BR></SPAN></FONT></DIV>
<DIV><FONT class=Apple-style-span face=georgia><SPAN class=Apple-style-span
style="FONT-SIZE: 13px">You can have a look to this paper you probably
know:</SPAN></FONT></DIV>
<DIV><FONT class=Apple-style-span face=georgia><SPAN class=Apple-style-span
style="FONT-SIZE: 13px">E.R. Johnson, JCP </SPAN></FONT><B>131</B>, 034111
2009</DIV>
<DIV><FONT class=Apple-style-span face=georgia><SPAN class=Apple-style-span
style="FONT-SIZE: 13px"><BR></SPAN></FONT></DIV>
<DIV><FONT class=Apple-style-span face=georgia><SPAN class=Apple-style-span
style="FONT-SIZE: 13px">I don't believe a cure to you problem exists at the
moment, except by changing the functional to a GGA one.</SPAN></FONT></DIV>
<DIV><FONT class=Apple-style-span face=georgia><SPAN class=Apple-style-span
style="FONT-SIZE: 13px"><BR></SPAN></FONT></DIV>
<DIV><SPAN class=Apple-style-span
style="FONT-SIZE: 13px; FONT-FAMILY: georgia">Best regards,</SPAN></DIV>
<DIV><FONT class=Apple-style-span face=georgia><SPAN class=Apple-style-span
style="FONT-SIZE: 13px"><BR></SPAN></FONT></DIV>
<DIV><FONT class=Apple-style-span face=georgia><SPAN class=Apple-style-span
style="FONT-SIZE: 13px">Yves</SPAN></FONT></DIV>
<DIV><FONT class=Apple-style-span face=georgia><SPAN class=Apple-style-span
style="FONT-SIZE: 13px">. </SPAN></FONT></DIV>
<DIV><FONT class=Apple-style-span face=georgia><SPAN class=Apple-style-span
style="FONT-SIZE: 13px"><BR></SPAN></FONT></DIV>
<DIV><FONT class=Apple-style-span face=georgia><SPAN class=Apple-style-span
style="FONT-SIZE: 13px"><BR></SPAN></FONT>
<DIV>
<DIV>Le 31 oct. 2014 à 09:26, Juanjo Meléndez a écrit :</DIV><BR
class=Apple-interchange-newline>
<BLOCKQUOTE type="cite">
<DIV dir=ltr>
<DIV dir=ltr>
<DIV style="FONT-SIZE: 12pt; FONT-FAMILY: 'Calibri'; COLOR: #000000">
<DIV>Hi Pascal</DIV>
<DIV> </DIV>
<DIV>Thanks for replying. I agree with you that building a PP consistent
with the metaGGA functional would solve most of the instability problems.
But I do not have *any* experience building PPs (which, by the way, seems to
be not trivial to me, even less trivial for metaGGA), so I followed <A
title=http://dx.doi.org/10.1016/j.cpc.2013.02.020
style="TEXT-ALIGN: justify"
href="http://dx.doi.org/10.1016/j.cpc.2013.02.020">http://dx.doi.org/10.1016/j.cpc.2013.02.020</A>
and tried the trick. I was just wondering if any general strategy for
convergence exists. </DIV>
<DIV> </DIV>
<DIV>Regarding point 2, I asked one of the authors of the aforementioned
paper and he declared not the have seen such a problem before, so I guess
that the kinetic terms are not responsible. I have overcome the problem by
using a dense kpoints path already in scf calculations and calculating the
bands without the standard intermediate nscf run, but it would be nice if
the developers could have a look and check. </DIV>
<DIV> </DIV>
<DIV>Again, thank you very much for your interest.</DIV>
<DIV> </DIV>
<DIV>Juanjo</DIV>
<DIV> </DIV>
<DIV style="FONT-SIZE: 12pt; FONT-FAMILY: 'Calibri'; COLOR: #000000">Juan J.
Meléndez <BR>Associate Professor<BR>Department of Physics · University of
Extremadura<BR>Avda. de Elvas, s/n 06006 Badajoz (Spain)<BR>Phone: +34 924
28 96 55<BR>Fax: <A href="tel:+34924289651" target=_blank><A
href="tel:+34924289651" target=_blank>+34 924 28 96 51</A></A><BR>Email: <A
href="mailto:melendez@unex.es">melendez@unex.es</A><BR>Web: <A
href="http://materiales.unex.es/miembros/personal/jj-melendez/Index.html">http://materiales.unex.es/miembros/personal/jj-melendez/Index.html</A></DIV>
<DIV
style="FONT-SIZE: small; FONT-FAMILY: 'Calibri'; FONT-WEIGHT: normal; COLOR: #000000; FONT-STYLE: normal; TEXT-DECORATION: none; DISPLAY: inline">
<DIV style="FONT: 10pt tahoma">
<DIV><FONT size=3 face=Calibri></FONT> </DIV>
<DIV style="BACKGROUND: #f5f5f5">
<DIV style="font-color: black"><B>From:</B> <A
title=pascal.boulet@univ-amu.fr
href="mailto:pascal.boulet@univ-amu.fr">Pascal BOULET</A> </DIV>
<DIV><B>Sent:</B> Thursday, October 30, 2014 7:15 PM</DIV>
<DIV><B>To:</B> <A title=pw_forum@pwscf.org
href="mailto:pw_forum@pwscf.org">PWSCF Forum</A> </DIV>
<DIV><B>Subject:</B> Re: [Pw_forum] TB09 metaGGA</DIV></DIV></DIV>
<DIV> </DIV></DIV>
<DIV
style="FONT-SIZE: small; FONT-FAMILY: 'Calibri'; FONT-WEIGHT: normal; COLOR: #000000; FONT-STYLE: normal; TEXT-DECORATION: none; DISPLAY: inline">
<DIV>
<DIV style="FONT-SIZE: 13px; FONT-FAMILY: georgia; COLOR: #000000">hello,
<DIV> </DIV>
<DIV>I have never tried meta-GGA functionals with QE, so I am guessing.
</DIV>
<DIV> </DIV>
<DIV>For point 1, one possible reason is the inadequacy between the pseudo
potential and the functional. I guess you have build a special
pseudopotential for this functional.</DIV>
<DIV> </DIV>
<DIV>Point 2: Could it be because the meta-GGA kinetic terms are not saved
in the checkpoint file and hence not readable when doing the
nscf?<BR><BR><BR>Pascal</DIV>
<DIV> </DIV>
<DIV>
<DIV> </DIV>
<DIV dir=ltr>"Juanjo Meléndez" <<A
href="mailto:melendez@unex.es">melendez@unex.es</A>> wrote:
<BLOCKQUOTE cite=x-msg://4/%3CBA0A7E01AFE046D08178A05800725F9D@Otello%3E
type="cite">
<DIV dir=ltr>
<DIV style="FONT-SIZE: 12pt; FONT-FAMILY: 'Calibri'; COLOR: #000000">
<DIV>Hi all</DIV>
<DIV> </DIV>
<DIV align=justify>I am starting to work with metaGGA functionals in QE
(v. 5.1 + libXc), following Èric Germaneau and colleagues’ work (<A
title=http://dx.doi.org/10.1016/j.cpc.2013.02.020
href="http://dx.doi.org/10.1016/j.cpc.2013.02.020">http://dx.doi.org/10.1016/j.cpc.2013.02.020</A>).
I know that metaGGA is little tested, but I would be pleased if somebody
could answer a couple of questions:</DIV>
<DIV align=justify> </DIV>
<DIV align=justify>1) Convergence is quite tricky. Up to know, I got some
results in simple systems using a very small mixing_beta (within
0.01–0.05), not too many bands (just one or two conduction bands, never
converged for more bands) and restarting from a previously fully converged
calculation. I got results only for carbon, silicon and germanium, never
got any convergence for any binary simple compound (like LiF). Does anyone
have additional hints for metaGGA calculations to converge?</DIV>
<DIV align=justify> </DIV>
<DIV align=justify>2) In addition, I get something wrong with nscf
calculations. After convergence of a scf run, I get a list of bands at
each k-point, as usual –nothing strange here. Then I made a path of
k-points to get the band structure and run a nscf calculation. This
finishes fine as well, but the bands are not only different from those
from the scf calculations, but also unrealistically high. I am attaching
the input and output files for both the scf and nscf runs, as well as a
couple of eigenval.xml files taken after nscf. Does anybody know how to
manage this? Or could this be a bug in the code?</DIV>
<DIV> </DIV>
<DIV>Thanks a lot in advance</DIV>
<DIV> </DIV>
<DIV>Take care</DIV>
<DIV> </DIV>
<DIV>Juanjo</DIV>
<DIV> </DIV>
<DIV style="FONT-SIZE: 12pt; FONT-FAMILY: 'Calibri'; COLOR: #000000">Juan
J. Meléndez <BR>Associate Professor<BR>Department of Physics · University
of Extremadura<BR>Avda. de Elvas, s/n 06006 Badajoz (Spain)<BR>Phone: +34
924 28 96 55<BR>Fax: <A href="tel:+34924289651" target=_blank>+34 924 28
96 51</A><BR>Email: <A
href="mailto:melendez@unex.es">melendez@unex.es</A><BR>Web: <A
href="http://materiales.unex.es/miembros/personal/jj-melendez/Index.html">http://materiales.unex.es/miembros/personal/jj-melendez/Index.html</A></DIV>
<DIV
style="FONT-SIZE: 12pt; FONT-FAMILY: 'Calibri'; COLOR: #000000"> </DIV>
<DIV
style="FONT-SIZE: 12pt; FONT-FAMILY: 'Calibri'; COLOR: #000000">****************************</DIV>
<DIV style="FONT-SIZE: 12pt; FONT-FAMILY: 'Calibri'; COLOR: #000000">“All
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<DIV
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<DIV style="FONT-SIZE: 10px; FONT-FAMILY: arial; COLOR: #000000"><FONT
size=2><FONT size=1></FONT><BR>>-----------------<BR>Pascal
Boulet<BR>Aix-Marseille University <BR>MADIREL Laboratory<BR>Avenue
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