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[Licence| Download | New Version Template] aatb_v1_0.gz(15 Kbytes)
Manuscript Title: Reduction of orbital sets.
Authors: E. Francisco, L. Seijo, L. Pueyo
Program title: OFMO
Catalogue identifier: AATB_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 43(1987)269
Programming language: Fortran.
Computer: HP1000/45F.
Operating system: RTE-6/VM.
RAM: 36K words
Word size: 16
Peripherals: disc.
Keywords: Molecular physics, Integral, Basis set generation, Overlap's maximization, Lagrange multipliers.
Classification: 16.10.

Nature of problem:
Given a set of atomic or molecular orbitals {psioi}, the program finds another orthonormal set, {psi i}, expressed in terms of a reduced basis {chi i}, that has maximum overlap with the given set.

Solution method:
The new set {Psi i}, is found by maximization of the overlap integrals <Psi i|Psi oi> with the orthogonality constraints <Psi i|Psi j> = Delta ij. The method of the undetermined Lagrange multipliers is used. Starting with a trial basis set {Chi}, the maximization is carried out with respect to the expansion coefficients connecting {Psi i} and {Chi i}. An analytical matrix equation is found for these coefficients. The nonlinear parameters of the basis {Chi i} are then optimized by means of an iterative process.

Restrictions:
The reference set {Psi oi} must be expressed in terms of Slater type orbitals(STO's) or Gaussian type orbitals(GTO's). When the {Psi oi} are made of STO's, the {Psi i} can be generated over STO's or GTO's. However, if the {Psi oi} are made of GTO's, the {Psi i} are generated over GTO's.

Unusual features:
None.

Running time:
53 s for the test run (with three cases).