title: Canonical density matrix perturbation theory.
abstract: Density matrix perturbation theory [Niklasson and Challacombe, Phys. Rev. Lett. 92, 193001 (2004)] is generalized to canonical (NVT) free-energy ensembles in tight-binding, Hartree-Fock, or Kohn-Sham density-functional theory. The canonical density matrix perturbation theory can be used to calculate temperature-dependent response properties from the coupled perturbed self-consistent field equations as in density-functional perturbation theory. The method is well suited to take advantage of sparse matrix algebra to achieve linear scaling complexity in the computational cost as a function of system size for sufficiently large nonmetallic materials and metals at high temperatures.
authors.affiliation: Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: Anders M N
authors.initials: AM
authors.lastname: Niklasson
authors.affiliation: Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Cawkwell
authors.affiliation: Division of Scientific Computing, Department of Information Technology, Uppsala University Box 337, SE-751 05 Uppsala, Sweden.
authors.forename: Emanuel H
authors.initials: EH
authors.lastname: Rubensson
authors.affiliation: Division of Scientific Computing, Department of Information Technology, Uppsala University Box 337, SE-751 05 Uppsala, Sweden.
authors.forename: Elias
authors.initials: E
authors.lastname: Rudberg