<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META http-equiv=Content-Type content="text/html; charset=iso-8859-1">
<META content="MSHTML 6.00.2900.2802" name=GENERATOR>
<STYLE></STYLE>
</HEAD>
<BODY bgColor=#ffffff>
<DIV><FONT face=Arial size=2>Hello Wien Users,</FONT></DIV>
<DIV><FONT face=Arial size=2>In doing volume optimisations I found that derived
cell dimensions are very sensitive to RMT. For example when I optimised the
structure of a cubic SiC with RMT 1.8 I get optimised a,b,c ~ 4.1
A. When I reduced RMT to 1.4, I get optimised a, b, c ~3.6 A. This is a
large change.</FONT></DIV>
<DIV><FONT face=Arial size=2>My question is how small should one go with RMT
reduction? How much smaller than the covalent radius can RMT go (Si = 1.1
A)? Do I keep reducing it till I get the lowest energy crystal size? I am
interested in deriving total energy and cell diemnsions.</FONT></DIV>
<DIV><FONT face=Arial size=2>I have read the Optimisation Notes by Marks
(highly useful) and the FAQ by Blaha but perhaps I have missed a
point.</FONT></DIV>
<DIV><FONT face=Arial size=2>Please suggest.</FONT></DIV>
<DIV><FONT face=Arial size=2>Thank you in anticipation.</FONT></DIV>
<DIV><FONT face=Arial size=2>Chandrika</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT size=2><FONT
face=Arial>-----------------------------------------------------------------------------------------<BR></FONT><FONT
face=Arial size=1>Dr (Ms) Chandrika Varadachari<BR>Raman Centre for Applied and
Interdisciplinary Sciences<BR>16A Jheel Road<BR>Calcutta 700075<BR>India<BR>Tel
: 91-33-24830029<BR>Fax : 91-33-24180610<BR>web : </FONT><A
href="http://www.rcais.org.in"><FONT face=Arial
size=1>www.rcais.org.in</FONT></A></FONT></DIV></BODY></HTML>