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504. NBO:Natural Bond-Orbital Wavefunction Analysis
Program
by Alan E. Reed and Frank Weinhold, Theoretical
Chemistry Institute and Department of Chemistry,
University of Wisconsin, Madison, Wisconsin 53706
This is a program for analyzing molecular wavefunctions
by the methods of Refs. 1-4 in terms of natural atomic
orbitals (NAOs), natural bond orbitals (NBOs), natural
localized molecular orbitals (NLMOs), and natural
population analysis (NPA). The NBO/NLMO analysis
results in orthonormal localized (NAO, NBO) and semi-
localized (NLMO) functions that compactly describe the
electron density, are intrinsic to the wave function
rather than the choice of basis set and are well
adapted to analysis in "chemical" terms. The natural
population occupancies of NAOs provide an alternative
to Mulliken population analysis. The NBOs represent
localized cores, lone pairs, bonds, antibonds, and
Rydberg orbitals of an optimized Lewis structure,
useful in performing an energetic analysis of the SCF
Fock matrix as provided in the program. The NLMOs are
an efficient alternative to other LMO procedures, such
as those of Boys or Edmiston and Ruedenberg.
Although the NBO/NLMO analysis is intended primarily
for ab initio SCF or CI wave functions (such as those
calculated by the GAUSSIAN 82 program), it may be
adapted to other semi-empirical or pseudopotential
methods that lead to a 1-particle density matrix. The
nucleus of this package is G82NBO, the set of programs
needed to integrate NBO/NLMO analysis into the GAUSSIAN
82 program system. Source code is also included for a
generic version of the program, which can be used to
analyze wavefunctions from other program systems.
Extensive provision is made for handling higher angular
symmetry basis orbitals ("pure", "Cartesian", "cubic",
etc.), up to d functions.
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References:
1. J. P. Foster and F. Weinhold, J. Am. Chem. Soc.,
102, 7211 (1980).
2. A. E. Reed and F. Weinhold, J. Chem. Phys., 78,
4066 (1983).
3. A. E. Reed, R. B. Weinstock, and F. Weinhold, J.
Chem. Phys., 83, 735 (1985).
4. A. E. Reed and F. Weinhold, J. Chem. Phys., 83,
1736 (1985).
FORTRAN
Lines of Code: 8,500
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