A general p-electron (Mulliken-like) population analysis

Abstract A generalization of the one-electron Mulliken population analysis is given. The number of the electron p-ads (i.e. dyads, triads etc.) which occupy the various subsets of p-atomic spin orbitals of a molecular system is examined. Easily programmable relations are derived allowing a general p-electron population analysis. The calculation (and storage) of the extremely large density matrix in AO space is avoided. Our process, involving two steps, can be applied to both orthogonal and non-orthogonal AO basis sets; in the latter case, a Mulliken-like partition is adopted. A numerical application is given for the correlated ground state of the CH4 molecule; the two- and three-electron population analysis is given in non-orthogonal AOs.

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