If I remember correctly, for Si, LDA gives a larger lattice constant than experiment (I am not sure). As far as I know, it is not guaranteed that LDA should always underestimates lattice parameters.<br><br>Javad Hashemifar<br>
<br><div class="gmail_quote">On Mon, Jul 13, 2009 at 5:27 PM, Bipul Rakshit <span dir="ltr"><<a href="mailto:bipulrr@gmail.com">bipulrr@gmail.com</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;">
Dear PWSCF users,<br>
Generally LDA underestimate the lattice constant and GGA overestimate<br>
it. But is it possible that for some materials, LDA also overestimate<br>
the lattice constants, when compared with experimental value?<br>
<br>
regards<br>
<br>
--<br>
Bipul Rakshit<br>
Research Fellow,<br>
Barkatullah University,<br>
Bhopal 462026,<br>
MP, India<br>
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</blockquote></div><br><br clear="all"><br>-- <br>======================================<br>Seyed Javad Hashemifar<br>Physics Department, Isfahan University of Technology<br>84156-83111 Isfahan, Iran<br>Tel: +98 311 391 2375 Fax:+98 311 3912376<br>
Email: <a href="mailto:hashemifar@cc.iut.ac.ir">hashemifar@cc.iut.ac.ir</a><br>Homepage: <a href="http://hashemifar.iut.ac.ir">http://hashemifar.iut.ac.ir</a><br>---------------------------------------------------------------------------<br>