[molpro-user] Computing higher roots in MRCI

[Gerald Knizia]

On Friday 10 April 2009 21:12, Jaffe, Richard L. (ARC-TSN) wrote:
> I am interested in computing the 6th root of B2 symmetry in non-linear C3.
> I can determine the first 6 roots, but I am trying to reduce computational
> cost by obtaining accurate solution only for the 6th root.

I don't know much about Molpros diagonalization routines, but from a purely 
numerical standpoint I would guess that this is impossible. I'm not aware of 
any matrix diagonalization algorithm that can calculate a specific 
eigenvector without also calculating all lower (or all higher) ones.
-- 
Gerald Knizia