[molpro-user] MRCI convergence problems with AlO

[Alexander Mitrushchenkov]

Lorenzo,

Usually this relates to problems with the choice of active space and orbitals.
Especially orbitals should be carefully verified, as minimal input often do not
provide good ones. Recently, we have calculated a number of AlO states at MRCI 
level (Mol.Phys.,105,1239(2007)). If you wish, I'll try to find the inputs that 
worked for us.

Best wishes,

Sasha

On Thursday 29 September 2011 16:57:12 Lorenzo Lodi wrote:
> Hello, in my group we are trying to compute the ground-state potential
> energy curve for AlO using MRCI. Please find attached a minimal-size
> input file and corresponding output. Starting from the 3rd iteration
> MRCI complains that
> ?EXPECTATION VALUE AND EIGENVALUE NOT IDENTICAL
> 
> and eventually stops the execution saying:
> 
> CI VECTOR FOR STATE 1 DOES NOT OVERLAP SUFFICIENTLY WITH REFERENCE VECTORS
> It may help to increase NSTATI, e.g., use OPTION,NSTATI=2
> 
> Can anybody explain briefly the meaning (and possible reason) for this
> error?
> We tried several reference spaces (all of the CAS type), increasing the
> suggested NSTATI and/or using shifts but nothings makes this behaviour
> go away.
> 
> Note that with the same reference space choices RS3 or NEVPT2 converge
> without problems.
> 
> Any suggestion will be welcome!
> 
> Best regards,
> Lorenzo

-- 
Dr. Alexander Mitrushchenkov, IGR
Laboratoire de Modélisation et Simulation Multi Echelle
UMR 8208 CNRS
Université Paris-Est Marne-la-Vallée
5 Bd Descartes
77454 Marne la Vallée, Cedex 2, France

Phone:    +33(0)160957316
Fax:      +33(0)160957320
e-mail:   Alexander.Mitrushchenkov at univ-mlv.fr
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