title: A Locality Analysis of the Divide-Expand-Consolidate Coupled Cluster Amplitude Equations.
abstract: We present a thorough locality analysis of the divide-expand-consolidate amplitude equations for second-order Møller-Plesset perturbation theory and the coupled cluster singles doubles (CCSD) model, which demonstrates that the amplitude equations are local when expressed in terms of a set of local occupied and local unoccupied Hartree-Fock orbitals, such as the least-change molecular basis. The locality analysis thus shows that a CC calculation on a large molecular system may be carried out in terms of CC calculations on small orbital fragments of the total molecular system, where the sizes of the orbital fragment spaces are determined in a black box manner to ensure that the CC correlation energy is calculated to a preset energy threshold. A practical implementation of the locality analysis is described, and numerical results are presented, which demonstrate that both the orbital fragment sizes and the relative energy error compared to a full CC calculation are independent of the molecular system size.
authors.affiliation: Lundbeck Foundation Center for Theoretical Chemistry, Department of Chemistry, University of Aarhus , DK-8000 Århus C, Denmark.
authors.forename: Kasper
authors.initials: K
authors.lastname: Kristensen
authors.affiliation: Lundbeck Foundation Center for Theoretical Chemistry, Department of Chemistry, University of Aarhus , DK-8000 Århus C, Denmark.
authors.forename: Marcin
authors.initials: M
authors.lastname: Ziółkowski
authors.affiliation: Lundbeck Foundation Center for Theoretical Chemistry, Department of Chemistry, University of Aarhus , DK-8000 Århus C, Denmark.
authors.forename: Branislav
authors.initials: B
authors.lastname: Jansík
authors.affiliation: Lundbeck Foundation Center for Theoretical Chemistry, Department of Chemistry, University of Aarhus , DK-8000 Århus C, Denmark.
authors.forename: Thomas
authors.initials: T
authors.lastname: Kjærgaard
authors.affiliation: Lundbeck Foundation Center for Theoretical Chemistry, Department of Chemistry, University of Aarhus , DK-8000 Århus C, Denmark.
authors.forename: Poul
authors.initials: P
authors.lastname: Jørgensen