title: An Extension of the Hirshfeld Method to Open Shell Systems Using Fractional Occupations.
abstract: In this work, a new partitioning method is presented which allows one to calculate properties of radicals, in particular, atomic spin populations. The method can be seen as an extension of the Hirshfeld-I method [ Bultinck , P. et al. J. Chem. Phys. 2007 , 126 , 144111 ], in which the atomic weight functions, defining the atoms-in-molecules, are constructed by means of an iterative scheme in which the charges of the atoms-in-molecules are altered but the spin remains fixed. The Hirshfeld-I method is therefore not suitable for the calculation of atomic spin populations of open-shell systems. The new fractional occupation Hirshfeld-I (FOHI) uses an iterative scheme in which both the atomic charge and spin are optimized, resulting in a self-consistent method for the calculation of atomic spin populations. The results obtained with the FOHI method are compared with experimental results obtained using polarized neutron diffraction, thus serving as a validation of the FOHI method as well as the Hirshfeld definition of atoms-in-molecules in general.
authors.affiliation: Department of Chemistry, University of Antwerp, Universiteitsplein 1, B2610 Antwerp, Belgium.
authors.forename: D
authors.initials: D
authors.lastname: Geldof
authors.affiliation: Department of Chemistry, University of Antwerp, Universiteitsplein 1, B2610 Antwerp, Belgium.
authors.forename: A
authors.initials: A
authors.lastname: Krishtal
authors.affiliation: Department of Chemistry, University of Antwerp, Universiteitsplein 1, B2610 Antwerp, Belgium.
authors.forename: F
authors.initials: F
authors.lastname: Blockhuys
authors.affiliation: Department of Chemistry, University of Antwerp, Universiteitsplein 1, B2610 Antwerp, Belgium.
authors.forename: C
authors.initials: C
authors.lastname: Van Alsenoy