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 simple scheme for introducing long-range RPA correlation into density functional theory is proposed and tested, which provides good thermochemical results and models van derWaals interactions accurately.
Abstract: We recently demonstrated a connection between the random phase approximation (RPA) and coupled cluster theory [J. Chem. Phys. 129, 231101 (2008)]. Based on this result, we here propose and test a simple scheme for introducing long-range RPA correlation into density functional theory. Our method provides good thermochemical results and models van derWaals interactions accurately.
154 citations
TL;DR: In this paper, a multi-coefficient correlation method based on quadratic configuration interaction with single and double excitations (MC-QCISD) and basis sets using segmented contraction and having the same exponential parameters in the s and p spaces.
Abstract: This paper presents a multi-coefficient correlation method based on quadratic configuration interaction with single and double excitations (MC-QCISD) and basis sets using segmented contraction and having the same exponential parameters in the s and p spaces. The results are comparable to a previous multi-coefficient correlation method based on coupled cluster theory with less efficient correlation-consistent basis sets, and they are better than a previous multi-coefficient correlation method based on Moller−Plesset fourth order perturbation theory with single, double, and quadruple excitations with correlation-consistent basis functions. The mean unsigned error per bond of the MC-QCISD method is 0.72 kcal/mol. The new method should be very efficient for computing geometries of open-shell transition states.
153 citations
01 Jan 2010
TL;DR: Explicitly correlated MP2-F12 and CCSD(T)-F12 methods with orbital-pair-specific Slater type geminals are proposed in this paper. But the complexity and the extra computational cost as compared to corresponding calculations with a single geminal are minor.
Abstract: Explicitly correlated MP2-F12 and CCSD(T)-F12 methods with orbital-pair-specific Slatertype geminals are proposed. The fixed amplitude ansatz of Ten-no is used, and different exponents of the Slater geminal functions can be chosen for core-core, core-valence, and valencevalence pairs. This takes care of the different sizes of the correlation hole and leads to improved results when inner-shell orbitals are correlated. The complications and the extra computational cost as compared to corresponding calculations with a single geminal are minor. The improved accuracy of the method is demonstrated for spectroscopic properties of Br2, As2, Ga2, Cu2, GaCl, CuCl, and CuBr, where the d-orbitals are treated as core.
153 citations
TL;DR: In this paper, the authors investigated the accuracy that can be obtained if the CCSD coefficients are replaced by their MBPT(2) analogs and discussed some additional diagonal approximations that might prove especially useful in polymer calculations, and compared with traditional Green's function calculations based on a second order approximation to the irreducible self-energy.
Abstract: The time‐consuming step in coupled cluster Green’s function or equivalently equation of motion coupled cluster calculations of ionization potentials is the solution of the CCSD equations. We investigate here the accuracy that can be obtained if the CCSD coefficients are replaced by their MBPT(2) analogs. We discuss some additional diagonal approximations that might prove especially useful in polymer calculations, and compare with traditional Green’s function calculations based on a second order approximation to the irreducible self‐energy.
153 citations
TL;DR: In this article, the authors re-examined the CASPT2 calculations of the heats of formation of the isomeric benzynes by R. Lindh and M. Schutz and showed that the unrealistically low value reported for p -benzene (132.7 kcal/mol) is an artifact of the use of incorrect CASSCF and CASPT 2 energies for p-benzenes, as well as a flawed isodesmic reaction analysis.
152 citations