THIS INFORMATION IS OBSOLETE AND IS PROVIDED ONLY FOR ITS HISTORICAL VALUE

by James J. P. Stewart, Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow G1 1XL, Scotland

In SCF-MO methods, the exact eigenvectors are not needed until self-consistency is achieved.At intermediate stages, it is sufficient to generate vectors which will, in turn, give rise to the "correct" density matrix. DIAGG can be used for this. It uses on input a set of vectors resulting from an exact diagonalisation or from a previous call of DIAGG. The new vectors are "better" than the original set and, as the method is iterative, at self-consistency a single diagonalisation will yield the exact eigenvectors. A description of the method can be found in "Fast Semiempirical Calculations" by J.J.P. Stewart et al., J. Comp. Chem. (in press:tentative date of publication--May, 1982).

NOTE:This same routine is contained in QCPE 455.

FORTRAN IV: IBM, VAX Lines of Code: 137