Topic
Coupled cluster
About: Coupled cluster is a research topic. Over the lifetime, 6280 publications have been published within this topic receiving 301055 citations.
Papers published on a yearly basis
Papers
More filters
TL;DR: In this paper, a variety of different density functionals, namely B3LYP, B97-1, PBE0, HCTH, BLYP, BBE, LDA, and a recently derived improvement of the hCTH functional (HCTH38), as well as the standard abinitio Hartree-Fock and second-order Moller-Plesset perturbation theory methods were applied using a triple-ζ plus double polarisation basis set.
Abstract: Comparisons with the results of coupled cluster calculations were made to assess the quality of density functionals in predicting the electronic binding energies of H-bonded complexes. A variety of different density functionals, namely B3LYP, B97-1, PBE0, HCTH, BLYP, PBE, LDA and a recently derived improvement of the HCTH functional (HCTH38), as well as the standard abinitio Hartree–Fock and second-order Moller–Plesset perturbation theory methods were applied using a triple-ζ plus double polarisation basis set. Equilibrium structures, counterpoise corrected binding energies and harmonic frequencies were calculated for the (HF)2, (HCl)2, (H2O)2, (CO)(HF), (OC)(HF), (FH)(NH3), (ClH)(NH3), (H2O)(NH3) and (H3O+)(H2O) complexes. Although the hybrid methods performed well in general, the new HCTH38 functional as a pure GGA predicted binding energies of better quality than the B3LYP functional. Bond length changes and frequency shifts were compared to MP2 results.
218 citations
TL;DR: A number of recently developed theoretical methods for the calculation of vibrational energies and wave functions are reviewed, including vibrational configuration interaction (VCI), vibrational Møller-Plesset (VMP), and vibrational coupled cluster (VCC) theory.
Abstract: A number of recently developed theoretical methods for the calculation of vibrational energies and wave functions are reviewed. Methods for constructing the appropriate quantum mechanical Hamilton operator are briefly described before reviewing a particular branch of theoretical methods for solving the nuclear Schrodinger equation. The main focus is on wave function methods using the vibrational self-consistent field (VSCF) as starting point, and includes vibrational configuration interaction (VCI), vibrational Moller–Plesset (VMP) theory, and vibrational coupled cluster (VCC) theory. The convergence of the different methods towards the full vibrational configuration interaction (FVCI) result is discussed. Finally, newly developed vibrational response methods for calculation of vibrational contributions to properties, energies, and transition probabilities are discussed.
217 citations
TL;DR: High-order excitations have been studied in three multireference couple cluster theories built on the wave operator formalism and the BW and Mk methods are found to provide more accurate results than the state-universal SU approach at all levels of truncation of the cluster operator.
Abstract: For the first time high-order excitations (n>2) have been studied in three multireference couple cluster (MRCC) theories built on the wave operator formalism: (1) the state-universal (SU) method of Jeziorski and Monkhorst (JM) (2) the state-specific Brillouin-Wigner (BW) coupled cluster method, and (3) the state-specific MRCC approach of Mukherjee (Mk). For the H4, P4, BeH(2), and H8 models, multireference coupled cluster wave functions, with complete excitations ranging from doubles to hextuples, have been computed with a new arbitrary-order string-based code. Comparison is then made to corresponding single-reference coupled cluster and full configuration interaction (FCI) results. For the ground states the BW and Mk methods are found, in general, to provide more accurate results than the SU approach at all levels of truncation of the cluster operator. The inclusion of connected triple excitations reduces the nonparallelism error in singles and doubles MRCC energies by a factor of 2-10. In the BeH(2) and H8 models, the inclusion of all quadruple excitations yields absolute energies within 1 kcal mol(-1) of the FCI limit. While the MRCC methods are very effective in multireference regions of the potential energy surfaces, they are outperformed by single-reference CC when one electronic configuration dominates.
216 citations
TL;DR: In this article, the frequency-dependent electronic polarizabilities and first hyperpolarizabilities for CO and H 2 O have been investigated in coupled-cluster response theory calculations, and triple excitation effects have been considered by means of the CC3 model.
216 citations
TL;DR: In this article, the graphical techniques of spin algebras are combined with a diagrammatic approach based on the time independent Wick theorem to yield the spin-adapted form of the coupled cluster theory.
Abstract: The graphical techniques of spin algebras are combined with a diagrammatic approach based on the time independent Wick theorem to yield the spin‐adapted form of the coupled cluster theory. The general rules for the implementation of this formalism are formulated and illustrated on the basic coupled‐pair many‐electron theory pertaining to closed shell ground states, for which case the explicit spin‐adapted equations are derived. The advantages of the spin‐adapted form of the theory are discussed along with the new insights it affords.
215 citations