[molpro-user] mrci spin purity

[Peter Knowles]

In the MRCI method, the energies are obtained from a linear eigenvalue problem. Thus provided that the hamiltonian matrix is a representation from a basis that is closed under symmetry operations (spin or space), its eigenfunctions will be symmetry pure.  In the contracted MRCI method, it is sometimes possible to arrange for this not to be true, but normally, with a reference wavefunction that is a definite symmetry, you should not expect symmetry breaking.

Peter

> On 5 Feb 2015, at 19:03, Martin Spenke <martinspenke at yahoo.de> wrote:
> 
> Dear all, 
> 
> is the mrci calculation in molpro purified from contributions of higher spin multiplicities
> when computing excitation energy of a singlet spin state ?
>  
> Bests
> Martin
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--
Prof. Peter J. Knowles             
School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK
Telephone: +44 29 208 79182
Email: KnowlesPJ at Cardiff.ac.uk 

Yr Athro Peter J. Knowles
Yr Ysgol Cemeg, Prifysgol Caerdydd,
Prif Adeilad, Plas y Parc
Caerdydd CF10 3AT, DU
Ffôn: +44 2920 879182
Ebost: KnowlesPJ at Caerdydd.ac.uk
Ysgrifennwch ataf yn Gymraeg neu Saesneg