Dear LAPACK,
I have been using subroutines dsyev and dsyevd to compute the eigenvectors
and eigenvalues of a symmetric 8x8 matrix. the matrix formed by these
eigenvectors should form a unitary matrix and therefore be the basis of a
unitary transformation. When I test the unitariy of the resulting matrix I
find that it is quite inaccurate. In particular I find that the scalar
product of two of the eigenvectors is 3.8D5. this is far less accurate
than I would like. As I need to perform at least 40,000 unitary
transformations in my dynamical calculations such a large error allows a
large buildup of errors and renders my calculations invalid.
All my variables are double precision. Can you advise as to how I can
improve the accuracy of my eigenvectors.
Gabriel BalintKurti
Professor of Theoretical Chemistry

Gabriel BalintKurti
Centre for Computational Chemistry
School of Chemistry
University of Bristol
Bristol, BS8 1TS
Tel: +44 117 928 7662
fax: +44 117 925 1295
Gabriel.BalintKurti@Domain.Removed
