Determination of Local Spins by Means of a Spin-Free Treatment

D.R. ALCOBA; A. TORRE; L. LAIN; R.C. BOCHICCHIO

JOURNAL OF CHEMICAL THEORY AND COMPUTATION

AMER CHEMICAL SOC

Lugar: Washington; Año: 2011 vol. 7 p. 3560 - 3566

1549-9618

This work describes a Mulliken-type partitioning of the expectation value of the spin-squared operator corresponding to anN-electron system. Our algorithms, which are based on a spin-free formulation, predict appropriate spins for the molecular fragments (at equilibrium geometries and at dissociation limits) and can be applied to any spin symmetry. Numerical determinations performed in selected closed- and open-shell systems at correlated level are reported. A comparison between these results and their counterpart ones arising from other alternative approaches is analyzed in detail.