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Browsing College of Sciences and Mathematics by Author "Pawlowski, Filip"

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Cluster perturbation theory. I. Theoretical foundation for a coupled cluster target state and ground-state energies 

Pawlowski, Filip; Olsen, Jeppe; Jorgensen, Poul; 0000-0002-5928-2140 (2020-05-20)
We introduce a new class of perturbation models-the cluster perturbation (CP) models-where the major drawbacks of Moller-Plesset perturbation theory and coupled cluster perturbation theory have been eliminated. In CP theory, ...

Cluster perturbation theory. II. Excitation energies for a coupled cluster target state 

Pawlowski, Filip; Olsen, Jeppe; Jorgensen, Poul; 0000-0002-5928-2140 (2020-05-07)
In cluster perturbation (CP) theory, we consider a target excitation space relative to a Hartree-Fock state and partition the target excitation space into a parent excitation space and an auxiliary excitation space. The ...

Cluster perturbation theory. III. Perturbation series for coupled cluster singles and doubles excitation energies 

Baudin, Pablo; Pawlowski, Filip; Bykov, Dmytro; Liakh, Dimitry; Kristensen, Kasper; Olsen, Jeppe; Jorgensen, Poul; 0000-0002-5928-2140 (2020-05-07)
The cluster perturbation series, CPS(D), for coupled cluster singles and doubles excitation energies is considered. It is demonstrated that the second-order model CPS(D-2) is identical to the configuration interaction ...

Cluster perturbation theory. IV. Convergence of cluster perturbation series for energies and molecular properties 

Pawlowski, Filip; Olsen, Jeppe; Jorgensen, Poul; 0000-0002-5928-2140 (2020-05-20)
The theoretical foundation has been developed for establishing whether cluster perturbation (CP) series for the energy, molecular properties, and excitation energies are convergent or divergent and for using a two-state ...

Cluster perturbation theory. V. Theoretical foundation for cluster linear target states 

Pawlowski, Filip; Olsen, Jeppe; Jorgensen, Poul; 0000-0002-5928-2140 (2020-05-20)
Cluster perturbation (CP) theory was developed in Paper I [F. Pawlowski et al., J. Chem. Phys. 150, 134108 (2019)] for a coupled cluster (CC) target state and is extended in this paper to comprehend a cluster linear (CL) ...