Communications: Accurate and efficient approximations to explicitly correlated coupled-cluster singles and doubles, CCSD-F12

Hättig, Christof; Tew, David P.; Köhn, Andreas

doi:10.1063/1.3442368

Cited by 288 publications

(313 citation statements)

References 20 publications

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“…Explicitly correlated coupled cluster singles and doubles with perturbative triples (CCSD(T)(F12*)) calculations were performed with Turbomole 6.5 [103][104][105][106] using the cc-pVDZ-F12 107 basis set as well as the corresponding auxiliary basis sets. 108 The Hartree-Fock contribution was corrected with the complementary auxiliary basis set (CABS) singles approach of Knizia and Werner.…”

Section: Quantum Chemical Methods and Qce Protocolmentioning

confidence: 99%

Quantum cluster equilibrium model of N-methylformamide–water binary mixtures

Domaros

Jähnigen

Friedrich

et al. 2016

The Journal of Chemical Physics

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The established quantum cluster equilibrium (QCE) approach is refined and applied to Nmethylformamide (NMF) and its aqueous solution. The QCE method is split into two iterative cycles: one which converges to the liquid phase solution of the QCE equations and another which yields the gas phase. By comparing Gibbs energies, the thermodynamically stable phase at a given temperature and pressure is then chosen. The new methodology avoids metastable solutions and allows a different treatment of the mean-field interactions within the gas and liquid phases. These changes are of crucial importance for the treatment of binary mixtures. For the first time in a QCE study, the cis-trans-isomerism of a species (NMF) is explicitly considered. Cluster geometries and frequencies are calculated using density functional theory (DFT) and complementary coupled cluster single point energies are used to benchmark the DFT results. Independent of the selected quantum-chemical method, a large set of clusters is required for an accurate thermodynamic description of the binary mixture. The liquid phase of neat NMF is found to be dominated by the cyclic trans-NMF pentamer, which can be interpreted as a linear trimer that is stabilized by explicit solvation of two further NMF molecules. This cluster reflects the known hydrogen bond network preferences of neat NMF. C 2016 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license

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Section: Quantum Chemical Methods and Qce Protocolmentioning

confidence: 99%

Quantum cluster equilibrium model of N-methylformamide–water binary mixtures

Domaros

Jähnigen

Friedrich

et al. 2016

The Journal of Chemical Physics

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“…69 The SP ansatz (also called the fixed amplitude or diagonal orbital invariant ansatz), in conjunction with STG, greatly simplifies the implementation and has been used in various CC models with Lagrangian functionals. [70][71][72][73][74][75] These have also been expanded into F12 adaptations in local correlation pictures, as we will outline later. Note the rational generator is a spin-free operator that does not contain the spin index s. This feature permits the application ofR 12 to open-shell references involving unrestricted HF (UHF), 76,77 restricted open-shell HF (ROHF), 74,78,79 and multi-determinant [80][81][82][83][84][85] wave functions in the manner of spinflipped geminal 73,77 and internally contracted 80 bases.…”

Section: Introductionmentioning

confidence: 99%

Perspective: Explicitly correlated electronic structure theory for complex systems

Grüneis

Hirata

Ohnishi

et al. 2017

The Journal of Chemical Physics

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The explicitly correlated approach is one of the most important breakthroughs in ab initio electronic structure theory, providing arguably the most compact, accurate, and efficient ansatz for describing the correlated motion of electrons. Since Hylleraas first used an explicitly correlated wave function for the He atom in 1929, numerous attempts have been made to tackle the significant challenges involved in constructing practical explicitly correlated methods that are applicable to larger systems. These include identifying suitable mathematical forms of a correlated wave function and an efficient evaluation of many-electron integrals. R12 theory, which employs the resolution of the identity approximation, emerged in 1985, followed by the introduction of novel correlation factors and wave function ansätze, leading to the establishment of F12 theory in the 2000s. Rapid progress in recent years has significantly extended the application range of explicitly correlated theory, offering the potential of an accurate wave-function treatment of complex systems such as photosystems and semiconductors. This perspective surveys explicitly correlated electronic structure theory, with an emphasis on recent stochastic and deterministic approaches that hold significant promise for applications to large and complex systems including solids. Published by AIP Publishing. [http://dx

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“…The level of correlation treatment is unchanged, while the basis set limit for the parameterization of the double excitations is approached more rapidly than for standard methods. The reason that F12 methods achieve near basis set limit accuracy with relatively small basis sets is because the F12 basis functions efficiently describe the sharp features of the wave function in the region of short-range r 12 , that is, the correlation cusp. In this way, the X −3 energy convergence of the orbital expansion is accelerated to X −7 for F12 methods, where X is the cardinal number of the orbital basis set.…”

Section: F12 Basis Functionsmentioning

confidence: 99%

“…Two-body electronelectron interactions are accounted for through double excitations, where a pair of occupied spin orbitals |ij is replaced by a linear combination of pair functions |ab , where a, b are virtual spin orbitals. The essence of F12 theory is to use a basis of pair functions |w xy in addition to the standard pair basis |ab , where |w xy depends explicitly on r 12 , the distance between two electrons. The level of correlation treatment is unchanged, while the basis set limit for the parameterization of the double excitations is approached more rapidly than for standard methods.…”

Section: F12 Basis Functionsmentioning

confidence: 99%

“…Equation (86) ensures that the error in the energy is quadratic in the density-fitting error and is therefore referred to as robust. The generalization of robust density fitting to the two-electron integrals required in MP2-F12 theory was developed by Manby 30 and can be cast into such a form that the number of transformation and contraction steps is minimal, 31 (ip|f 12 …”

Section: Density Fittingmentioning

confidence: 99%

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The MP2‐F12 method in the TURBOMOLE program package

et al. 2011

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Abstract:A detailed description of the explicitly correlated second-order Møller-Plesset perturbation theory (MP2-F12) method, as implemented in the Turbomole program package, is presented. The Turbomole implementation makes use of density fitting, which greatly reduces the prefactor for integral evaluation. Methods are available for the treatment of ground states of open-and closed-shell species, using unrestricted as well as restricted (open-shell) Hartree-Fock reference determinants. Various methodological choices and approximations are discussed. The performance of the Turbomole implementation is illustrated by example calculations of the molecules leflunomide, prednisone, methotrexate, ethylenedioxytetrafulvalene, and a cluster model for the adsorption of methanol on the zeolite H-ZSM-5. Various basis sets are used, including the correlation-consistent basis sets specially optimized for explicitly correlated calculations (cc-pVXZ-F12).

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Communications: Accurate and efficient approximations to explicitly correlated coupled-cluster singles and doubles, CCSD-F12

Abstract: We propose a novel explicitly correlated coupled-cluster singles and doubles method CCSD(F12(*)), which retains the accuracy of CCSD-F12 while the computational costs are only insignificantly larger than those for a conventional CCSD calculation.

Cited by 288 publications

References 20 publications

Quantum cluster equilibrium model of N-methylformamide–water binary mixtures

Quantum cluster equilibrium model of N-methylformamide–water binary mixtures

Perspective: Explicitly correlated electronic structure theory for complex systems

The MP2‐F12 method in the TURBOMOLE program package

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