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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.
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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).
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