Subject: Re: CCL:the ground state calculation with g98

From: Petr Toman <ccl)at(linus.imcm.cas.cz>
Date: Thu, 26 Jun 2003 20:28:56 +0200 (CEST)

Hello,

Do you use a spin restricted or unrestricted method?
If restricted, try the unrestricted one and use Guess=Alter
only for the exchange of beta HOMO and LUMO, although you
expect a closed shell. I had a similar problem with some
cations of Metal-phthalocyanines
(you can see P. Toman, S. Nespurek, K. Yakushi: 
J. Porphyrins Phthalocyanines 2002; 6: 556-562) 

Btw. what molecule do you calculate? 

Yours,
Petr Toman

On Fri, 13 Jun 2003, Dai Bing wrote:

> Dear CCLers,
>    A simple Opt calculation with g98, HOMO and LUMO are the
> same symmetry, such as PI. But the energy of LUMO is lower than
> the one of HOMO, what's the problem? and how to resolve?
>    The following two methods don't work. :(
>    1. Stable=opt.
>    2. change the symmetry of the molecule, HOMO and LUMO
> change to A1 and B1, then use guess=alter.
> 
>    Can someone help me? Thanks.
> 
> = = = = = = = = = = = = = = = = = = = =
> 
> ===============
> Bing Dai,
> Ph.D. Candidate,
> Laboratory of Bond Selective Chemistry,
> University of Science and Technology of China,
> Chinese Academy of Sciences.
> Hefei, Anhui, 230026,
> People's Republic of China,
> Tel.: 86-551-3603418,3603748,3601084
> Fax.: 86-551-3602969
> Http://www.bsc.ustc.edu.cn/~bdai
> E-mail: bdai)at(mail.ustc.edu.cn
> ===============
> 
> 
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