|
466. DNMR4: Calculation of Chemically Exchanging
Spectra
by C. Hackett Bushweller, Leo J. Letendre, Jacques A.
Brunelle, Howard S. Bilofsky, Michael R. Whalon and
Stephen H. Fleischman, Department of Chemistry,
University of Vermont, Burlington, Vermont 05405
DNMR4, a program for the calculation of chemical
exchange NMR spectra, is a modification of DNMR3 (D. A.
Kleier and G. Binsch, QCPE 165). The modifications are
all intended to decrease CPU time and memory usage and
improve numerical stability.
These modifications involved replacing the eigenproblem
subroutine ALLMAT with the EISPAK routines CBAL,
COMHES, COMLR2 and CBABK2. In addition, the similarity
transformation "trick" described by Gerhard Binsch in
J. Mag. Resonance, 30, 625 (1978) was implemented to
avoid explicit inversion of the eigenvector matrix.
This required inclusion of the subroutine DEGEN to
search for degenerate eigenvalues and the Schmidt
orthogonalization of the corresponding eigenvectors.
The complex matrices have been separated into two real
matrices, and much of the arithmetic is thus real
instead of complex. Memory usage was decreased
approximately 30%, and CPU time usage was decreased up
to 60%. We removed the coding that automatically
averaged the spectra if the rate constant was 1000
times the largest chemical shift difference.
Furthermore, the intensities are normalized to allow
the separate calculation of noncoupled subspectra and
the subsequent plotting of the additive spectra.
FORTRAN (ANSI)
Lines of Code: 2490
|
