Dear Mariusz,
Thank you for your reply. I am trying to locate a open-shell
singlet transition state by using UDFT. What else that I need to
check in order to confirm that it is the correct broken symmetry singlet
state, other than the correct occupation of singly alpha and beta orbitals
and the non-zero <S**2> vaule.
Thanks a lot
Sue
--- On Thu, 7/31/08, Mariusz Radon mariusz.radon-,-gmail.com
<owner-chemistry-$-ccl.net> wrote:
From: Mariusz Radon mariusz.radon-,-gmail.com
<owner-chemistry-$-ccl.net>
Subject: CCL:G: Locating a broken-symmetry
singlet state in Gaussian
To: "L, Sue "
<chsue2004-$-yahoo.com>
Date: Thursday, July 31, 2008, 5:16
PM
Sent to CCL by: Mariusz Radon [mariusz.radon~~gmail.com]
Sue L chsue2004:yahoo.com wrote:
> Is it necessary to put a keyword guess=mix, in order to locate a
> broken-symmetry singlet state in Gaussian? If the molecule contains a
> symmetry, in which the singly occupied alpha and beta orbitals are in
> different symmetry, there is no need to put that keyword?
>
Hi Sue,
Is it enough or not, I think, it depends on particular case... You
always need to check whether you really have converged to a
broken-symmetry solution or not; AFAIK, even "guess=mix" keyword
doesn't
guarantee this. So, you need to inspect the molecular orbitals and/or
<S**2> value after the calculations are finished.
In such a case, that alpha and beta singly occupied orbitals belong to
different symmetries, a nice way to produce the broken symmetry solution
might be to manually permute the relevant orbitals (e.g.
"guess=alter")
and (probably) to use "scf=symm".
best wishes,
Mariusz Radonhttp://www.ccl.net/cgi-bin/ccl/send_ccl_messagehttp-:-//www.ccl.net/chemistry/sub_unsub.shtmlhttp-:-//www.ccl.net/spammers.txt |