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278. SPUHF: Brickstock-Pople UHF Calculation with
Harriman Spin Projection Treatment
by J. C. Schug, D. H. Phillips, and D. A. Brewer,
Virginia Polytechnic Institute and State University,
Blacksburg, Virginia 24061
This program performs an unrestricted Hartree-Fock
calculation on a planar pi-electron system using PPP
approximations. The first atom is located at the
origin. Other atoms are positioned by using plane
polar coordinates with an origin on any previously
located atom.The program transforms these to
Cartesian coordinates and calculates electron repulsion
integrals using the selected method. The off-diagonal
core Hamiltonian matrix elements are read in as data.
Initial orbitals are estimated by a Hückel calculation.
Iterative SCF calculations are then carried out until
the energy is consistent to 10-6 eV or until the
desired maximum number of iterations have been carried
out. There is an option to employ a non-Aufbau
approximation for the density matrix at the first
iteration if this is desired.
Subroutine WATE performs spin projections for the
desired number of spin states, using the equations of
Harriman and coworkers. For each spin state, the
program calculates the energy of the projected state,
the charge density matrix, the diagonal elements of the
two-particle charge density matrix, and the projected
spin densities.
FORTRAN IV (IBM 360/370)
Lines of Code: 1272
Recommended Citation: J. C. Schug et al., QCPE 11, 278
(1975).
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