2002/09/20 by Anders M. N. Niklasson · 2 citations
Physics and Astronomy · #cond-mat.mtrl-sci
paper · pdf · doi:10.1103/physrevb.66.155115
5 pages, 4 figures, to appear in Phys. Rev. B
arxiv created 2002/09/20 · arxiv updated 2009/11/30
A purification algorithm for expanding the single-particle density matrix in terms of the Hamiltonian operator is proposed. The scheme works with a predefined occupation and requires less than half the number of matrix-matrix multiplications compared to existing methods at low (<10%) and high (>90%) occupancy. The expansion can be used with a fixed chemical potential in which case it is an asymmetric generalization of and a substantial improvement over grand canonical McWeeny purification. It is shown that the computational complexity, measured as number of matrix multiplications, essentially is independent of system size even for metallic materials with a vanishing band gap.