2003/11/30 by Anders M. N. Niklasson, Matt Challacombe · 3 citations
Physics and Astronomy · #Advanced Chemical Physics Studies #Spectroscopy and Quantum Chemical Studies #Theoretical and Computational Physics #cond-mat.mtrl-sci
paper · pdf · doi:10.1103/physrevlett.92.193001
4 pages, 2 figures
arxiv created 2003/12/03 · openalex publication_date 2004/05/14 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
An orbital-free quantum perturbation theory is proposed. It gives the response of the density matrix upon variation of the Hamiltonian by quadratically convergent recursions based on perturbed projections. The technique allows treatment of embedded quantum subsystems with a computational cost scaling linearly with the size of the perturbed region, O(N(pert.)), and as O(1) with the total system size. The method allows efficient high order perturbation expansions, as demonstrated with an example involving a 10th order expansion. Density matrix analogs of Wigner's 2n+1 rule are also presented.