Distribution of effectively unpaired electrons

The density of effectively unpaired electrons employed recently by the auth ors [J. Am. Chem. Sec. 122 (2000) 186] is identical with the distribution D (r) of 'odd' electrons proposed much earlier by Takatsuka, Fueno, and Yamag uchi [Theor. Chim. Acta 48 (1978) 175]. The function D(r/r') is also implic itly present in several definitions of the free valence index. Basic proper ties of D(r/r') are reviewed and a number of new results are reported. The distribution D(r) is advocated as a rigorous criterion of the radical chara cter in molecules of any spin. Numerical examples deal with the dissociatio n of N-2 and O-2 molecules. (C) 2000 Elsevier Science B.V. All rights reser ved.