<h3 class="gD" style="color: rgb(91, 16, 148);"><span>dear Lorenzo Paulatto</span></h3>Thank you for you clear explanation i understood it now. previously i was not clear how these fractions are coming but now it is clear. Thank you very much for your explanation <br>
<br><div class="gmail_quote">On Sat, Sep 12, 2009 at 1:45 PM, Lorenzo Paulatto <span dir="ltr"><<a href="mailto:paulatto@sissa.it">paulatto@sissa.it</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;">
<div class="im"><br>
On Sat, September 12, 2009 08:15, udayagiri sai babu wrote:<br>
> Dear all<br>
> Can somebody clearly tell me how to define occupations from input. I cant<br>
> find much about that in this forum. The card "occupations" described in<br>
> the<br>
> example 11 for Al is not at all clear to me. What are those values mean.<br>
> Looking forward to your help....<br>
<br>
<br>
</div>It's quite easy, actually, there are only a couple of points you have to<br>
keep in mind:<br>
<br>
1. if nspin=1 occupations can go from 0 to 2, you have to specify the<br>
occupation from the lower to the highest band and the sum of the<br>
occupations will have to be the number of electrons;<br>
<br>
2. if nspin=2 occupations go from 0 to 1, you specify the occupation for<br>
spin up first, then for spin down (always on a newline);<br>
<br>
Let's say you want to reproduce the calculation of the Cr isolated atom,<br>
with semicore states in valence: 3s2 3p6 4s1 3d5 4p0<br>
<br>
first with nspin=1 and spherical (as it is done in ld1.x):<br>
OCCUPATIONS<br>
2 2 2 2 1 1 1 1 1 1 0 0 0<br>
!3s2 3p6 4s1 3d5 4p0<br>
<br>
then spin polarized (nspin=2), according to Hund's rule you have to<br>
maximize the total angular momentum:<br>
OCCUPATIONS<br>
1 1 1 1 1 1 1 1 1 1 0 0 0<br>
1 1 1 1 0 0 0 0 0 0 0 0 0<br>
!3s2 3p6 4s1 3d5 4p0<br>
<br>
Chrome is a lucky case, as it has a spherical ground state. As a last<br>
example let's take an oxygen atom (2s2 2p4) and set the occupations to<br>
reproduce the ld1.x calculation:<br>
OCCUPATIONS<br>
2 4/3 4/3 4/3<br>
<br>
or, equivalently:<br>
OCCUPATIONS<br>
2 1.333333 1.333333 1.333334<br>
<br>
<br>
I hope it helps, best regards<br>
<br>
--<br>
Lorenzo Paulatto<br>
SISSA & DEMOCRITOS (Trieste)<br>
phone: +39 040 3787 511<br>
skype: paulatz<br>
www: <a href="http://people.sissa.it/%7Epaulatto/" target="_blank">http://people.sissa.it/~paulatto/</a><br>
<br>
<br>
<br>
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</div></div></blockquote></div><br><br clear="all"><br>-- <br>U.Saibabu<br>PhD student,<br>Deformation mechanisms modeling group,<br>Materials engineering department,<br>IISc Bangalore,<br>India.<br><br>