Subject: CCL: symmetry of wavefunction

From: "Petr Toman" <[email-masked]>
Date: Fri, 23 Jun 2000 10:12:59 +0200

Dear CCLers,
I am calculating the conformations of transition metal-phthalocyanine 
complexes (including ions and radicals) by means of Gaussian 98/94. 
I have a lot of difficulties with the preparing of the initial guess of 
the wavefunction. If I succeed to prepare a good guess with the full 
symmetry, the work goes well. (The resulting wavefunction usually has the 
full symmetry.)

Often, if I have worse but symmetrical initial guess, I get after one or 
several iterations the message

 Density matrix breaks symmetry, PCut= 1.00D-07
 Density has only Abelian symmetry.

or even

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

My question is: Is it possible to preserve the full symmetry during the 
iteration process? Is it possible to symmetrize the nearly symmetrical 
resulting wavefunction and use it as a guess for further calculations?
Is it possible to change the value PCut ?

Thank you in advance for any suggestions.

Yours, 
       Petr