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387. REX:Relativistically Parameterized Extended
Hückel Program
by Lawrence L. Lohr, Jr., Department of Chemistry,
University of Michigan, Ann Arbor, Michigan 48109; and
Matti Hotokka and Pekka PyykkO(,ö), Department of
Physical Chemistry, Åbo Akademi, 20500 Turku, Finland
This program performs REX calculations1 which include
both spin-orbit splitting and relativistic contractions
or expansions of the individual |j jj> orbitals.
Therefore, the matrices are twice as large as for the
ordinary EHT2 from which REX is constructed, and
complex arithmetic is necessary. Atomic orbitals of s,
p, d and f type may be used. Both relativistic and
non-relativistic calculations may be performed.
Relativistic single-z STO default parameters from
atomic Dirac-Fock calculations3 are provided for the
elements 1-120 and non-relativistic ones for 1-100.
Multiple-z functions may be specified by the user. A
Mulliken population analysis may be performed. All
instructions are given on COMMENT cards in MAIN.
The current version handles molecules with at most 30
atoms and 200 spin orbitals. It uses one scratch tape
and needs about 400 Kb of core memory.
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References:
1. L. L. Lohr, Jr., and P. Pyykkö, Chem. Phys. Lett.,
62, 333 (1979).
2. J. Howell, et al., QCPE 10, 344 (1973).
3. J. P. Desclaux, At. Data Nucl. Data Tables, 12, 311
(1973).
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FORTRAN V (UNIVAC 1108, DEC 10)
Lines of Code: 4000
Recommended Citation: L. L. Lohr, Jr., M. Hotokka and
P. Pyykkö, QCPE 13, 387 (1981).
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