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Tue May 11 17:31:48 CEST 2010
www.democritos.it/pipermail/pw_forum/2008-September/010123.html</a></div>
<div><a href=3D"http://www.democritos.it/pipermail/pw_forum/2010-February.t=
xt" target=3D"_blank">http://www.democritos.it/pipermail/pw_forum/2010-Febr=
uary.txt</a></div><div><br></div><div>I understand that the third derivativ=
es were never implemented and</div>
<div>that only the LDA part was calculated, for the Perdew Zunger</div><div=
>parameterization. Is this third derivative the third derivative that</div>=
<div>is mentioned in the routine PH/raman_mat.f90 (i.e, the third</div>
<div>derivative of the energy with respect to the atomic displacements and<=
/div><div>with respect to two electric fields, as described in Lazzeri and<=
/div><div>Mauri, PRL 90,036401)?</div><div><br></div><div>I am interested i=
n getting a feel for what would be needed to</div>
<div>implement the third derivatives with GGA into the code, as well as</di=
v><div>what sort of errors one might expect when using the third-order term=
</div><div>as currently coded with LDA pseudopotentials (comments in the fo=
rums</div>
<div>have hinted that the errors are likely small). =A0The shift in the Ram=
an</div><div>spectra for cd-Si is pretty minor when using a GGA pseudo comp=
ared to</div><div>that of an LDA calculation, but I wanted to be able to qu=
antify the</div>
<div>error better for other systems where comparing the GGA raman spectra</=
div><div>to one calculated within LDA was not possible (e.g., when the syst=
em</div><div>doesn't exhibit a gap in LDA).</div><div><br></div><div>
Thanks for the help!</div><div><br></div><div>Best,</div><div>Brad</div><di=
v>UC Berkeley</div></div></div><div><div></div><div class=3D"h5"><div><div>=
<br></div><br><div class=3D"gmail_quote">On Tue, Nov 9, 2010 at 5:59 PM, Br=
ad Malone <span dir=3D"ltr"><<a href=3D"mailto:brad.malone at gmail.com" ta=
rget=3D"_blank">brad.malone at gmail.com</a>></span> wrote:<br>
<blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p=
x #ccc solid;padding-left:1ex">It appears that my last email was severely t=
runcated on the mailing list (even though it looks fine in my outbox). Belo=
w is what is should have been:<div>
-----------------------</div><div><div><div></div><div><span style=3D"font-=
family:arial, sans-serif;font-size:13px;border-collapse:collapse;color:rgb(=
51, 51, 51)">Hi, I am seeking more information on the error<br>
<br>> from phq_setup : error # 1<br>> third order derivatives not imp=
lemented with GGA<br><br>From the forums:<br><br><a href=3D"http://www.demo=
critos.it/pipermail/pw_forum/2008-September/010123.html" style=3D"color:rgb=
(61, 84, 89)" target=3D"_blank">http://www.democritos.it/pipermail/pw_forum=
/2008-September/010123.html</a><br>
<a href=3D"http://www.democritos.it/pipermail/pw_forum/2010-February.txt" s=
tyle=3D"color:rgb(61, 84, 89)" target=3D"_blank">http://www.democritos.it/p=
ipermail/pw_forum/2010-February.txt</a><br><br>I understand that the third =
derivatives were never implemented and<br>
that only the LDA part was calculated, for the Perdew Zunger<br>parameteriz=
ation. Is this third derivative the third derivative that<br>is mentioned i=
n the routine PH/raman_mat.f90 (i.e, the third<br>derivative of the energy =
with respect to the atomic displacements and<br>
with respect to two electric fields, as described in Lazzeri and<br>Mauri, =
PRL 90,036401)?<br><br>I am interested in getting a feel for what would be =
needed to<br>implement the third derivatives with GGA into the code, as wel=
l as<br>
what sort of errors one might expect when using the third-order term<br>as =
currently coded with LDA pseudopotentials (comments in the forums<br>have h=
inted that the errors are likely small). =A0The shift in the Raman<br>spect=
ra for cd-Si is pretty minor when using a GGA pseudo compared to<br>
that of an LDA calculation, but I wanted to be able to quantify the<br>erro=
r better for other systems where comparing the GGA raman spectra<br>to one =
calculated within LDA was not possible (e.g., when the system<br>doesn'=
t exhibit a gap in LDA).<br>
<br>Thanks for the help!<br><br>Best,<br>Brad<br>UC Berkeley</span><br><br>=
</div></div><div><div></div><div><div class=3D"gmail_quote">On Tue, Nov 9, =
2010 at 5:00 PM, Brad Malone <span dir=3D"ltr"><<a href=3D"mailto:brad.m=
alone at gmail.com" target=3D"_blank">brad.malone at gmail.com</a>></span> wro=
te:<br>
<blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p=
x #ccc solid;padding-left:1ex">Hi, I am seeking more information on the err=
or<br>
<br>
> from phq_setup : error # 1<br>
> third order derivatives not implemented with GGA<br>
<br>
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