From owner-chemistry@ccl.net Sat Nov 19 18:19:01 2005
From: "Yingbin Ge yingbin.ge(-)gmail.com" <owner-chemistry!A!server.ccl.net>
To: CCL
Subject: CCL: Is CASSCF appropriate for study of PES?
Message-Id: <-30008-051119165925-2548-L6/squ2cTO7JKhqREP/lDA!A!server.ccl.net>
X-Original-From: Yingbin Ge <yingbin.ge%%gmail.com>
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Date: Sat, 19 Nov 2005 15:59:17 -0600
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Sent to CCL by: Yingbin Ge [yingbin.ge_+_gmail.com]
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Hi CCLers,
 I am studying the PES of a small molecule and wondering
whether CASSCF or CASPT2//CASSCF is an appropriate
method for the PES study since these methods are not
size consistent thus not good at calculating the dissociation
energies accurately. Another downside of using CAS is that there
is no easy way of consistently choosing virtual orbitals into the active
space
for molecules with only sigma bonds and lone pair electrons.
 Any comments please?
 Thanks a lot!
Yingbin

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<div>Hi CCLers,</div>
<div>&nbsp;</div>
<div>I am studying the PES of a small molecule and wondering</div>
<div>whether CASSCF or CASPT2//CASSCF is an appropriate</div>
<div>method for the PES study since these methods are not</div>
<div>size consistent thus not good at calculating the dissociation</div>
<div>energies accurately. Another downside of using CAS&nbsp;is that there<=
/div>
<div>is no&nbsp;easy way of consistently choosing virtual orbitals into the=
 active space</div>
<div>for molecules with only sigma bonds and lone pair electrons.</div>
<div>&nbsp;</div>
<div>Any comments please?</div>
<div>&nbsp;</div>
<div>Thanks a lot!</div><span class=3D"sg">
<div>Yingbin</div></span>

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