FUKUTOME SYMMETRY CLASSIFICATION OF THE KOHN-SHAM AUXILIARY ONE-MATRIX AND ITS ASSOCIATED STATE OR ENSEMBLE

The Kohn-Sham (KS) procedure for Variational minimization of the Hohen berg-Kohn density functional utilizes a one-particle reduced density m atrix of assumed diagonal form, hence depends implicitly on a set of a uxiliary states. Originally, the auxiliary state was assumed to be a s ingle determinant with doubly occupied spin orbitals, i.e., of the sam e form as in ''restricted'' Hartree-Fock theory. The pragmatic and for mal extension of the KS procedure to noninteger occupation numbers req uires extension to more general forms of the auxiliary state or even i ts replacement by an auxiliary ensemble. Though attention has been giv en to the symmetry properties of the KS one-matrix, its spin and time- reversal symmetries have not been classified along the lines of Fukuto me's treatment of the generalized Hartree-Fock problem. Here we show t hat, in the context of constrained search density functional theory (D FT), Fukutome's analysis goes through essentially unaltered. We then c onsider the broken symmetry consequences for the case that the KS one- matrix is restricted to a single-determinantal KS auxiliary state. (C) 1998 John Wiley & Sons, Inc. Int J Quant Chem 69: 451-460, 1998.