Thank you so much Dr. Marzari and Lorenzo....<br><br><div class="gmail_quote">On Wed, Nov 25, 2009 at 6:01 PM, Nicola Marzari <span dir="ltr"><<a href="mailto:marzari@mit.edu">marzari@mit.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<br>
Dear Mohnish,<br>
<br>
roughly speaking you should use a similar degauss for m-v and gaussian.<br>
.05 Ry is fairly large, I'd stick with<br>
.02 Ry or so.<br>
<br>
Try this - study a bulk system (i.e. as small as possible) and plot for<br>
3 or 4 k-point meshes the free energy (E-TS)<br>
as a function of smearing. At very small smearings the free energy will<br>
not be converged with respect to k-points;<br>
at high smearings it will, but will also be very dependent on smearing.<br>
<br>
You want the sweet spot in between.<br>
<br>
nicola<br>
<div><div></div><div class="h5"><br>
<br>
mohnish pandey wrote:<br>
> Dear users,<br>
> I have calculated the energy of zinc oxide thin<br>
> film having nine layers. But the energy calculated by "m-v" and<br>
> "gaussian" smearing is coming out to be very different. The difference<br>
> is around 0.1 Rydberg. I have used used "degauss" to be .05 and 10^-3<br>
> respectively for "m-v" and "gaussain smearing". Can anybody please<br>
> tell me why the energy is coming out to be very different. I have gone<br>
> through the sections of book by Martin and Sholl also but I couldnt<br>
> find that.<br>
><br>
> Sincere thanks in advance.<br>
> Mohnish Pandey<br>
><br>
><br>
> --<br>
> Mohnish Pandey<br>
> Y6262,4th Year Undergraduate,<br>
> Department of Chemical Engineering,<br>
> IIT KANPUR<br>
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---------------------------------------------------------------------<br>
Prof Nicola Marzari Department of Materials Science and Engineering<br>
13-5066 MIT 77 Massachusetts Avenue Cambridge MA 02139-4307 USA<br>
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</div></div></blockquote></div><br><br clear="all"><br>-- <br>Mohnish Pandey<br>Y6262,4th Year Undergraduate,<br>Department of Chemical Engineering,<br>IIT KANPUR<br>