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468. QATREX: Relativistically Parameterized Extended
Hückel Program Employing Quaternionic Algebra
by Notker Rösch, Lehrstuhl für Theoretische Chemie,
Technische Universität München, D-8046 Garching, FRG
This program performs REX calculations as described by
L. L. Lohr, Jr. and P. Pyykkö, Chem. Phys. Lett., 62,
333 (1979). The program exhibits all features of QCPE
387 from which it has been constructed, but differs
from its precursor in the following:
1. Time reversal symmetry is fully taken into account
during diagonalization by employing quaternionic
algebra, as shown by N. Rösch, Chem. Phys. (in
press). One quaternionic eigenvector represents
both spin orbitals of a Kramers degenerate pair.
2. The code has been reorganized at various places
(especially in the calculation of the overlap
matrix) to further reduce core space and execution
time.
3. The code fulfills (with two rather minor
exceptions which have been indicated) the ANSI
standard of FORTRAN 77
The current version is dimensioned for molecules with
up to 30 atoms and, at most, 100 spin orbitals. About
40K words of core memory are required (plus I/O
buffers). Instructions for changing dimensions and for
constructing the input are given as COMMENT cards in
the main program. The program uses one sequential
scratch file.
FORTRAN 77 (CDC FTN5)
Lines of Code: 3900
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