Second-order variational coupled-cluster linear-response method: A Hermitian time-dependent theory

Journal Article · Wed Jun 15 04:00:00 EDT 2011 · Physical Review. A

DOI:https://doi.org/10.1103/PHYSREVA.83.062503· OSTI ID:21550092

Kats, Daniel; Usvyat, Denis; Schuetz, Martin ^[1]

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1. Institute of Physical and Theoretical Chemistry, University of Regensburg, Universitaetsstrasse 31, D-93040 Regensburg (Germany)

The formalism is presented for the linear response of a time-dependent (TD) variational coupled cluster (VCC), truncated according to Moeller-Plesset perturbation theory, i.e., a TD-VCC[n] linear response, where n denotes the order of the corresponding quasienergy with respect to the fluctuation potential. The resulting eigenvalue problem determining the excitation energies is Hermitian and of the simple Tamm-Dancoff form. The VCC excitation energies are equivalent to those of the configuration-interaction singles (CIS) model, while the Casida equation for the TD-Hartree-Fock approach is an approximation to it. The TD-VCC response, the lowest-order method including electron correlation, is discussed in detail and the relations to other second-order methods, such as the CC2 linear response and the algebraic diagrammatic construction at second order [ADC(2)] are explored.

• OSTI ID: 21550092
• Journal Information: Physical Review. A, Journal Name: Physical Review. A Journal Issue: 6 Vol. 83; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
APPROXIMATIONS
CALCULATION METHODS
CLUSTER MODEL
CONFIGURATION INTERACTION
CORRELATIONS
EIGENVALUES
ELECTRON CORRELATION
ENERGY-LEVEL TRANSITIONS
EXCITATION
FLUCTUATIONS
FUNCTIONS
HARTREE-FOCK METHOD
HERMITE POLYNOMIALS
MATHEMATICAL MODELS
NUCLEAR MODELS
PERTURBATION THEORY
POLYNOMIALS
POTENTIALS
TIME DEPENDENCE
VARIATIONAL METHODS
VARIATIONS