Subject: Re: Gaussain 94 Error Message

From: Jaouad El-Bahraoui <[email-masked]>
Date: Tue, 9 Jun 1998 07:12:43 +0300 (EET DST)

Hi Melissa and CCl's
A while ago I asked the below question:

Does any one know how to solve this kind of problem in g94, I use the
version E.2

 Density matrix breaks symmetry, PCut= 1.00D-04
 Density matrix has no symmetry -- integrals replicated.
 Density matrix breaks symmetry, PCut= 1.00D-04
 Density matrix has no symmetry -- integrals replicated.

Here I present the summary of responses, and by the way I want to thanks
all who gives me a little of his time to solve my problem.

all the Best
Jaouad

***************************************************************************
                            summary
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On Fri, 5 Jun 1998, Melissa Petersen wrote:

> Hi Jaouad,
> 
> I have just joined the computational chemistry list and I noticed that you
> posted a message on 25 May concerning an error that you got in g94 i.e.
> "Density Matrix breaks symmetry"
> 
> I have also been experiencing this problem. Could you tell me if you have
> received any replies? I was not able to find any replies in the message
> archives.
> 
> Thanks in anticipation.
> Melissa Petersen
> 
> ********************************************************************************
> ********************************************************************************
> Catalysis Research Unit
> Department of Chemical Engineering
> University of Cape Town
> Private Bag, Rondebosch, 7701
> Cape Town
> South Africa
> 
> Email: [email-masked]
> or    [email-masked]
> ****************************************************************************************************************************************************************

>From [email-masked] Tue Jun  9 06:53:38 1998
Date: Mon, 25 May 1998 16:23:42 +0100 (GDT)
From: [email-masked]
To: Jaouad El-Bahraoui <[email-masked]>
Subject: Re: CCL:G:G94 problem.....

Hi!

Your problem may be a numerical one.

 Density matrix breaks symmetry, PCut= 1.00D-04
 Density matrix has no symmetry -- integrals replicated.
 Density matrix breaks symmetry, PCut= 1.00D-04
 Density matrix has no symmetry -- integrals replicated.

It arises if the integrals must be the same in a certain symmetry, but
they are not. So one hint is to tell the scf-procedure to calculate
integrals with respect to symmetry: scf=(intrep)

This can be keyword  connected to scf=(symm). This one frozens 
configurations and is a powerful tool to get crazy things.
Be careful.

Alex

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>From [email-masked] Tue Jun  9 06:53:49 1998
Date: Tue, 26 May 1998 01:42:04 +1000
From: Danne R Rasmussen <[email-masked]>
To: Jaouad El-Bahraoui <[email-masked]>
Subject: Re: CCL:G:G94 problem.....

a few options:  

a) if you are reading in a guess (using guess=read or guess=check) then
don't,
b) try using SCF=novaracc i.e. use best integral accuracy at all steps in
the SCF,
c) if you are doing DFT try SCF=vshift and/or SCF=(vshift,novaracc),
d) if you are using many diffuse functions in a large molecule try using a
different basis set; diffuse functions can cause convergence problems due to
linear dependence etc,
e) (risky) if you think you should have symmetry but keep running into
problems (i.e. all the above failed) try modifying PCut in the G94 source
and recompiling l502 [PCut=1.0D-03 will do it but you risk getting false
symmetry].  you can put your special l502.exe in your own home directory
(e.g. ~/g94/l502.exe) and modify GAUSS_EXEDIR to include ~/g94 earlier in
the path than the $root/g94 directory then your own l502.exe will be used
instead of the default executable.  

good luck,

danne

>From [email-masked] Tue Jun  9 06:53:55 1998
Date: Mon, 25 May 1998 21:11:30 +0200
From: Krzysztof Radacki <[email-masked]>
To: Jaouad El-Bahraoui <[email-masked]>
Subject: Re: CCL:G:G94 problem.....

As far as I know it means that during geometry optimization you have lost
symmetry. Try to start without symmetry (NoSymm flag in command line) 
for example:

#P RHF/6-31++G(d,p) opt=z-matrix Nosymm

regards
Krzys Radacki

>From [email-masked] Tue Jun  9 06:54:00 1998
Date: Tue, 26 May 1998 09:09:21 +0930 (CST)
From: Brian Salter-Duke <[email-masked]>
To: Jaouad El-Bahraoui <[email-masked]>
Subject: Re: CCL:G:G94 problem.....

Hi,

1. Check everything. Have you got the right state you want?
2. Do you have an ion? If so do the parent closed shell molecule
and use guess=read to get the starting vectors. Maybe try reading
the coefficients from a smaller basis set.

Cheers, Brian.
-- 
        Associate Professor Brian Salter-Duke (Brian Duke)
School of Mathematical and Physical Sciences, Northern Territory University,
          Darwin, NT 0909, Australia.  Phone (61) (0)8-89466702
e-mail: [email-masked]  or [email-masked]

>From [email-masked] Tue Jun  9 06:54:05 1998
Date: Tue, 26 May 1998 06:48:54 +0200
From: Megan Govender <[email-masked]>
To: [email-masked], [email-masked]
Subject: Re: CCL:G:G94 problem.....

Hi....

I also had that same problem optimizing compounds of Uranium some time back...
Are you trying similar calculations?...I used to use opt=fp with 
the nosymm option for these type calculations to get around this
problem. Hope this helps...

Regards
Magan

>From [email-masked] Tue Jun  9 06:54:20 1998
Date: Wed, 27 May 1998 12:40:11 +0200
From: Visnja Simek <[email-masked]>
To: Jaouad El-Bahraoui <[email-masked]>
Subject: Re: CCL:G:G94 problem.....

Do you put "NoSym" in # line in addition to other keywords ?

                              Best regards,
                                               Visnja 

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Visnja Simek
Laboratory of Molecular Spectroscopy
Rudjer Boskovic Institute
P.O.B. 1016, Zagreb
CROATIA

Tel: (385-1) 456 09 44
Fax: (385-1) 468 00 84
     (385-1) 468 01 95
E-mail: [email-masked]
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