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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. _________ 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 |