Subject: Re: CCL:Basis sets for transitional metals

From: John Bushnell <bushnell=at=chem.ucsb.edu>
Date: Fri, 19 Mar 2004 13:54:17 -0800 (PST)

Problems with convergence of systems with transition metals are probably
due to bad guesses of the orbital populations by Gaussian rather than
the choice of basis set.  You may want to search the CCL archives for
tips on achieving convergence in problem cases.

Some things to try:
  scf=vshift
  scf=qc
  Do an rohf calculation first, then proceed from that guess. (guess=read)
  Increase the maximum number of scf cycles allowed.
  Look at the default guess (guess=only) and switch some of the orbitals
around to get a "correct"/better state. (guess=alter)
  Always try to do a single-point, loose scf convergence first.  Then
work from this, doing guess=alter as needed.  Consider that there may
be multiple electronic AND spin states possible.  The existence/location
of any ligands, etc. (the chemical environment) will alter the relative
energies of these states, so geometry can affect convergence.

    Hope that helps  -  John

On Fri, 19 Mar 2004, li wrote:

> 
>  Hi!
>  
>  I am using g98w now, and i find out that the basis sets shipped with
> g98w can not converge well with systems containing transitional metal
> atoms or transitional metal clusters. Can somebody give me some
> information on which basis sets are suitable for calculation of
> clusters containing Ni, Cu, Ag, Ti, Co atoms and can converge well in
> g98w?
>  
>  Thank you all for your future help
>  
>  Sincerely yours
>  
>  Xin,Liu
>