title: Idempotency-conserving iteration scheme for the one-electron density matrix.
abstract: For the first order density matrix P of a noninteracting N-electron problem, an iterative formula is presented that preserves the trace and idempotency of P so that no purification is needed. Hermiticity--which may be slightly violated in the course of the iteration--gets restored when the iteration converges and the converged P corresponds to the exact solution. For sparse P, the energy is obtained by an O(N) procedure that needs no prior knowledge of the chemical potential. Illustrative calculations in tight-binding and ab initio Hartree-Fock levels are presented.
authors.affiliation: Eötvös University, Department of Theoretical Chemistry, H-1518 Budapest 112, P.O.B. 32, Hungary.
authors.forename: Dóra
authors.initials: D
authors.lastname: Kohalmi
authors.forename: Agnes
authors.initials: A
authors.lastname: Szabados
authors.forename: Péter R
authors.initials: PR
authors.lastname: Surján