Thanks for the response, but not sure how useful it is.<br>To get the fermi smearing I set the following input lines<br><br>occupations='smearing'<br>smearing='fermi-dirac'<br>degauss=0.01 (fermi temperature in Ry, about 1500K, I want to set it higher also)<br>
<br>The smearing would ensure that states are no longer either fully occupied or empty. And I am not sure either of what you mean by commenting out check on LO-TO splitting and smearing. As I have used it before, as long as I don't specify smearing I get the LO-TO splitting automatically.<br>
<br><div class="gmail_quote">2012/4/13 Paolo Giannozzi <span dir="ltr"><<a href="mailto:giannozz@democritos.it">giannozz@democritos.it</a>></span><br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div class="im"><br>
On Apr 13, 2012, at 11:26 , Hans Lind wrote:<br>
<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
I am trying to do phonon calculations on AlN at non-zero fermi temperature<br>
to get forces recalculated for higher temperatures. But since I need to use<br>
smearing for that the code won't do LO-TO splitting as is needed in a<br>
semiconductor.<br>
</blockquote>
<br></div>
if you comment out the check on LO-TO splitting and smearing, and if all states are<br>
either fully occupied or empty, you should still get a LO-TO splitting. Not sure what<br>
it means, though. The phonon formalism is supposed to work at zero temperature.<br>
Not sure what it takes to extend the formalism to cover finite-temperature effects.<br>
<br>
P.<br>
---<br>
Paolo Giannozzi, Dept of Chemistry&Physics&Environment,<br>
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy<br>
Phone <a href="tel:%2B39-0432-558216" value="+390432558216" target="_blank">+39-0432-558216</a>, fax <a href="tel:%2B39-0432-558222" value="+390432558222" target="_blank">+39-0432-558222</a><br>
<br>
<br>
<br>
<br>
</blockquote></div><br>