Waelz, Gero and Kats, Daniel and Usvyat, Denis and Korona, Tatiana and Schuetz, Martin (2012) Application of Hermitian time-dependent coupled-cluster response Ansatze of second order to excitation energies and frequency-dependent dipole polarizabilities. PHYSICAL REVIEW A, 86 (5): 052519. ISSN 2469-9926, 2469-9934
Full text not available from this repository.Abstract
Linear-response methods, based on the time-dependent variational coupled-cluster or the unitary coupled-cluster model, and truncated at the second order according to the Moller-Plesset partitioning, i.e., the TD-VCC[2] and TD-UCC[2] linear-response methods, are presented and compared. For both of these methods a Hermitian eigenvalue problem has to be solved to obtain excitation energies and state eigenvectors. The excitation energies thus are guaranteed always to be real valued, and the eigenvectors are mutually orthogonal, in contrast to response theories based on "traditional" coupled-cluster models. It turned out that the TD-UCC[2] working equations for excitation energies and polarizabilities are equivalent to those of the second-order algebraic diagrammatic construction scheme ADC(2). Numerical tests are carried out by calculating TD-VCC[2] and TD-UCC[2] excitation energies and frequency-dependent dipole polarizabilities for several test systems and by comparing them to the corresponding values obtained from other second- and higher-order methods. It turns out that the TD-VCC[2] polarizabilities in the frequency regions away from the poles are of a similar accuracy as for other second-order methods, as expected from the perturbative analysis of the TD-VCC[2] polarizability expression. On the other hand, the TD-VCC[2] excitation energies are systematically too low relative to other second-order methods (including TD-UCC[2]). On the basis of these results and an analysis presented in this work, we conjecture that the perturbative expansion of the Jacobian converges more slowly for the TD-VCC formalism than for TD-UCC or for response theories based on traditional coupled-cluster models.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | ELECTRON CORRELATION METHODS; EXCITED-STATES; CONFIGURATION-INTERACTION; POLARIZATION PROPAGATOR; LOCAL TREATMENT; WAVE-FUNCTION; HARTREE-FOCK; SINGLES; EXPANSION; HYPERPOLARIZABILITIES; |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Physikalische und Theoretische Chemie Chemistry and Pharmacy > Institut für Physikalische und Theoretische Chemie > Research Group Theoretical Chemistry |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 04 May 2020 06:37 |
| Last Modified: | 04 May 2020 06:37 |
| URI: | https://pred.uni-regensburg.de/id/eprint/17731 |
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