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<div class="moz-cite-prefix">the third derivatives that are computed
in D3 are those of type d3E/du(q) du(-q) du(0) where at least one
q-vector is 0.<br>
For the generalization to any set of displacements you need to
wait for Lorenzo's contribution.<br>
<br>
stefano<br>
<br>
On 20/04/2016 14:51, Sabry Gad Al Hak Moustafa wrote:<br>
</div>
<blockquote
cite="mid:CAHFscESaHHtq4cRVPQx+hFtJfEWUOCSxsDg8-OJTCytnBFVtag@mail.gmail.com"
type="cite">
<div dir="ltr">Thanks Stefano;
<div><br>
</div>
<div>But, what do you mean by "some"? I am interested
specifically in Fe at high pressure, so, can QE do 3rd
derivative for that?</div>
<div><br>
</div>
<div>
<div style="font-size:12.8px">Here</div>
<div style="font-size:12.8px">
<div style="font-size:small"><span style="font-size:12.8px"><br>
</span></div>
<div style="font-size:small"><span style="font-size:12.8px"><a
moz-do-not-send="true"
href="http://www.quantum-espresso.org/wp-content/uploads/Doc/ph_user_guide.pdf"
target="_blank"><a class="moz-txt-link-freetext" href="http://www.quantum-espresso.org/wp-content/uploads/Doc/ph_user_guide.pdf">http://www.quantum-espresso.org/wp-content/uploads/Doc/ph_user_guide.pdf</a></a></span><br>
</div>
<div><br>
</div>
</div>
<div style="font-size:12.8px">it says</div>
<div style="font-size:12.8px"><br>
</div>
<div style="font-size:12.8px">"D3/d3.x: calculates anharmonic
phonon lifetimes (third-order derivatives of the energy),
using data produced by pw.x and ph.x (USPP and PAW not
supported)."<br>
</div>
</div>
<div><br>
</div>
<div>So, it looks like it is NCPP.</div>
<div><br>
</div>
<div>Thanks;</div>
<div>Sabry</div>
<div><br>
</div>
<div><br>
</div>
</div>
<div class="gmail_extra"><br clear="all">
<div>
<div class="gmail_signature">
<div dir="ltr"><span>==================================================<span><br>
</span><span>Sabry</span> G. <span>Moustafa</span>,
Ph.D.<br>
Department of Chemical and Biological Engineering<br>
<span>511</span> <span>Furnas</span> <span>Hall</span><br>
University at Buffalo, The State University of New York<br>
Buffalo, NY 14260-4200<br>
716-645-1186 (office)<br>
716-239-8543 (cell)<span
style="border-collapse:separate;border-spacing:0px">
<div style="word-wrap:break-word"><span
style="border-collapse:separate;border-spacing:0px">
<div style="word-wrap:break-word"><span
style="border-collapse:separate;border-spacing:0px">
<div style="word-wrap:break-word">
<div
style="color:rgb(0,0,0);font-size:12.8px"><span
style="font-size:12.8px">E-mail: </span><a
moz-do-not-send="true"
href="mailto:kofke@buffalo.edu"
style="font-size:12.8px" target="_blank"><a class="moz-txt-link-abbreviated" href="mailto:sabrygad@buffalo.edu">sabrygad@buffalo.edu</a></a></div>
</div>
</span></div>
</span></div>
</span></span></div>
</div>
</div>
<br>
<div class="gmail_quote">On Wed, Apr 20, 2016 at 12:28 AM,
stefano de gironcoli <span dir="ltr"><<a
moz-do-not-send="true" href="mailto:degironc@sissa.it"
target="_blank"><a class="moz-txt-link-abbreviated" href="mailto:degironc@sissa.it">degironc@sissa.it</a></a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF">
<div>the phonon code evaluates second order derivatives
(dynamical matrices).<br>
this is available for NCPP, USPP and PAW<br>
<br>
the D3 code computes some of the third order
derivatives.<br>
it is working for NCPP only as far as I remember.<br>
<br>
forth order derivatives are not computed.<br>
<br>
stefano
<div>
<div class="h5"><br>
<br>
On 20/04/2016 06:34, Sabry Gad Al Hak Moustafa
wrote:<br>
</div>
</div>
</div>
<blockquote type="cite">
<div>
<div class="h5">
<div dir="ltr">
<div><span style="font-size:12.8px">Hi;</span>
<div style="font-size:12.8px"><br>
<div>Was wondering if QE can compute 2nd, 3rd
and 4th energy derivatives in the DFPT
framework? If so, is available in PAW, or
just PPs?</div>
<div><br>
</div>
<div>Thanks;</div>
<div>Sabry</div>
<div><br>
</div>
</div>
</div>
<div><br>
</div>
<br clear="all">
<div>
<div>
<div dir="ltr"><span>==================================================<span><br>
</span><span>Sabry</span> G. <span>Moustafa</span>,
Ph.D.<br>
Department of Chemical and Biological
Engineering<br>
<span>511</span> <span>Furnas</span> <span>Hall</span><br>
University at Buffalo, The State
University of New York<br>
Buffalo, NY 14260-4200<br>
716-645-1186 (office)<br>
716-239-8543 (cell)<span
style="border-collapse:separate;border-spacing:0px">
<div style="word-wrap:break-word"><span
style="border-collapse:separate;border-spacing:0px">
<div style="word-wrap:break-word"><span
style="border-collapse:separate;border-spacing:0px">
<div
style="word-wrap:break-word">
<div
style="color:rgb(0,0,0);font-size:12.8px"><span
style="font-size:12.8px">E-mail:
</span><a
moz-do-not-send="true"
href="mailto:sabrygad@buffalo.edu"
target="_blank"><a class="moz-txt-link-abbreviated" href="mailto:sabrygad@buffalo.edu">sabrygad@buffalo.edu</a></a></div>
</div>
</span></div>
</span></div>
</span></span></div>
</div>
</div>
</div>
<br>
<fieldset></fieldset>
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</div>
</div>
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