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638. PEPA: Poly-Electron Population Analysis Program
by Padeleimon Karafiloglou, Faculty of Chemistry, P.O.B. 135, School of Sciences, Aristotelian University of Thessaloniki, GR-54006 Thessaloniki, Greece, and Ramón M. Parrondo and Enrique Sánchez Marcos, Department of Physical Chemistry, Faculty of Chemistry, University of Sevilla, 41012 Sevilla, Spain This program performs a general Poly-Electron Population Analysis in the framework of a partition similar to that of Mulliken for reduced density matrices of p-th order. The basis of this method has been previously reported1,2. Three quantities can be obtained from this program: 1. The occupation number Nf;0(k1k2...kF;) which corresponds to a collective electronic event, where F electrons are simultaneously occupying the Atomic Spin Orbitals (k1k2...kF). In the particular case of F=1, N1;0(k1) is the one-electron Mulliken population in the ASO k1. If the AO basis set is orthogonal, the occupation number becomes a probability. 2. The occupation number NF;E(k1k2...kF;l1l2...lE) which corresponds to a collective event where F electrons occupy the ASOs (k1k2...kF) and simultaneously there are E holes in the ASOs (l1l2...lE). 3. The contributions or weights of a local resonance structure, such as the different distributions of a chemical bond or a functional group inside a molecular system. Some examples of application of this analysis technique can be found elsewhere3-5. _________ References: 1. P. Karafiloglou, Chem. Phys., 128, 373 (1988). 2. P. Karafiloglou, Chem. Phys., 140, 373 (1990). 3. E. Sánches Marcos, P. Karafiloglou and J. Fernández Sanz, J. Phys. Chem., 94, 2763 (1990). 4. P. Karafiloglou and E. Sánchez Marcos, Int. J. Quantum Chem., 44, 337 (1992). 5. R. M. Parrondo, P. Karafiloglou and E. Sánchez Marcos, Int. J. Quantum Chem., 00, 000 (1993). |