Dear Prof. Peter Blaha,<div><br></div><div> Thank you very much for your reply. I got my answer.</div><div><br></div><div>with best regards,<br><br><div class="gmail_quote">On Tue, Jun 26, 2012 at 11:19 AM, Peter Blaha <span dir="ltr"><<a href="mailto:pblaha@theochem.tuwien.ac.at" target="_blank">pblaha@theochem.tuwien.ac.at</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Yes, U depends on the type of atom, but of course also on the specific compound.<br>
For metallic Fe the U should be in the range of 0-2 eV at most, for some insulating compound with very localized states, it may go up to even 4-6 (maybe even 8) eV.<br>
<br>
Am 26.06.2012 06:42, schrieb shamik chakrabarti:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div class="im">
Dear wien2k users,<br>
<br>
We generally choose the value of U by fitting it with<br>
experimental band gap or by calculating it through linear response<br>
method. Now my question is that whether U is element specific or depends<br></div>
on the composite in which the element reside? (*if I consider same<div class="im"><br>
magnetic configuration for all the composites I am referring here...as<br></div>
antiferromagntism do produce a band gap even without applying any U*)<div class="im"><br>
<br>
To make it more clear, say for Fe d, I have seen in literature, people<br>
have used U=4.5 to 5 eV......in some of our calculation we have even<br>
used U=6 eV for Fe d to obtain better electronic structure having closer<br>
match with experimental observation. Hence it looks that U for Fe d<br>
orbital can have value ranging from 4.5-6 eV...& that mean U is not<br>
element specific rather it depends on the composite in which the element<br>
exist (I again want to insist that if I consider same magnetic<br>
configuration for all the composites). Am I right?<br>
<br>
with regards,<br>
<br>
--<br>
Shamik Chakrabarti<br>
Senior Research Fellow<br>
Dept. of Physics & Meteorology<br>
Material Processing & Solid State Ionics Lab<br>
IIT Kharagpur<br>
Kharagpur 721302<br>
INDIA<br>
<br>
<br></div>
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<br>
</blockquote>
<br>
-- <br>
Peter Blaha<br>
Inst.Materials Chemistry<br>
TU Vienna<br>
Getreidemarkt 9<br>
A-1060 Vienna<br>
Austria<br>
+43-1-5880115671<br>
<br>
<br>
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</blockquote></div><br><br clear="all"><div><br></div>-- <br>Shamik Chakrabarti<br>Senior Research Fellow<br>Dept. of Physics & Meteorology<br>Material Processing & Solid State Ionics Lab<br>IIT Kharagpur<br>Kharagpur 721302<br>
INDIA<br>
</div>