Configuration-interaction study of atoms. I. Correlation energies of B, C, N, O, F, and Ne

Sasaki, Fukashi; Yoshimine, M.

doi:10.1103/physreva.9.17

Cited by 174 publications

(33 citation statements)

References 16 publications

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“…The RHF energies differ less than 0.5 x 10 -3 hartrees from the RHF limit (Froese-Fischer, 1977) yielding a virial ratio correct to at least six digits. Total SDCI and MR-SDCI energies for the elements Li to Ne deviate less than 1 x 10 -3 hartrees from the best hitherto published CI results (Sasaki & Yoshimine, 1974;Feller & Davidson, 1988, 1989Bunge, 1976). For the elements Na to Ar, no correlation calculations of comparable high quality have been published.…”

Section: Resultsmentioning

confidence: 54%

Accurate elastic scattering factors for lithium to argon based on correlated wavefunctions

Meyer¹,

Müller²,

Schweig³

1995

Acta Cryst Sect A

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Elastic scattering factors (or atomic form factors)f (s) for Li to Ar have been derived in the first Born approximation from ab initio MR-SDCI (multireference singly and doubly excited configuration interaction) calculations which recover between 90 and 99% of the estimated total correlation energy. The correlation effects on f(s) are contrasted with the relativistic effects known from the literature. Atomic form factors are presented that take into account correlation and relativistic contributions in an additive manner.

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Section: Resultsmentioning

confidence: 54%

Accurate elastic scattering factors for lithium to argon based on correlated wavefunctions

Meyer¹,

Müller²,

Schweig³

1995

Acta Cryst Sect A

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“…66 Analogously, in going to a higher order of approximation, quintuples and sextuples rather than just sextuples must be incorporated, even for closed-shell systems.…”

Section: A Determinantal CI and Oktay Singanoğlumentioning

confidence: 99%

“…As a numerical test, the Ne ground state is chosen because it is the simplest well known example 66,[79][80][81][82][83] exhibiting many of the complexities of a highly correlated CI. The basis set consists of 103 energy-optimized radial orbitals 79 up to ᐉ =13:12s12p11d10f10g9h8i7k6l5m4n3o3q3r, amounting to 1077 orbitals.…”

Section: A Choice Of Systemmentioning

confidence: 99%

Selected configuration interaction with truncation energy error and application to the Ne atom

Bunge

2006

The Journal of Chemical Physics

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Selected configuration interaction ͑SCI͒ for atomic and molecular electronic structure calculations is reformulated in a general framework encompassing all CI methods. The linked cluster expansion is used as an intermediate device to approximate CI coefficients B K of disconnected configurations ͑those that can be expressed as products of combinations of singly and doubly excited ones͒ in terms of CI coefficients of lower-excited configurations where each K is a linear combination of configuration-state-functions ͑CSFs͒ over all degenerate elements of K. Disconnected configurations up to sextuply excited ones are selected by Brown's energy formula,with B K determined from coefficients of singly and doubly excited configurations. The truncation energy error from disconnected configurations, ⌬E dis , is approximated by the sum of ⌬E K s of all discarded Ks. The remaining ͑connected͒ configurations are selected by thresholds based on natural orbital concepts. Given a model CI space M, a usual upper bound E S is computed by CI in a selected space S, and E M = E S + ⌬E dis + ␦E, where ␦E is a residual error which can be calculated by well-defined sensitivity analyses. An SCI calculation on Ne ground state featuring 1077 orbitals is presented. Convergence to within near spectroscopic accuracy ͑0.5 cm −1 ͒ is achieved in a model space M of 1.4ϫ 10 9 CSFs ͑1.1ϫ 10 12 determinants͒ containing up to quadruply excited CSFs. Accurate energy contributions of quintuples and sextuples in a model space of 6.5ϫ 10 12 CSFs are obtained. The impact of SCI on various orbital methods is discussed. Since ⌬E dis can readily be calculated for very large basis sets without the need of a CI calculation, it can be used to estimate the orbital basis incompleteness error. A method for precise and efficient evaluation of E S is taken up in a companion paper.

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“…In He, for example, important correlation effects can be accomplished by the polarizations, ( ) Many very accurate configuration interaction calculations have been carried out on atoms, molecules and clusters using large basis sets that include higher spherical harmonic functions. [1][2][3][4][5][6][7][8][9][10][11] As systems increase in size, the additional functions required for angular correlation cause a rapid increase in the number of configurations, limiting the applicability of the method.…”

Section: Methodsmentioning

confidence: 99%

“…There is a vast literature on ways to do this ranging from perturbation methods that generate configurations and evaluate energies efficiently to methods for partitioning large systems into localized electronic subspaces or ways to balance errors in systems that are being compared. [1][2][3][4][5][6][7][8][9][10][11] Relatively few configurations are required to dissociate molecules correctly or to create proper spin states. However, dynamical correlation effects, particularly those associated with angular correlation, require higher spherical harmonic basis functions and this leads to a rapid increase in number of interacting configurations.…”

Section: Introductionmentioning

confidence: 99%

Electron correlation by polarization of interacting densities

Whitten

2017

The Journal of Chemical Physics

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Coulomb interactions that occur in electronic structure calculations are correlated by allowing basis function components of the interacting densities to polarize dynamically, thereby reducing the magnitude of the interaction. Exchange integrals of molecular orbitals are not correlated. The modified Coulomb interactions are used in single-determinant or configuration interaction calculations. The objective is to account for dynamical correlation effects without explicitly introducing higher spherical harmonic functions into the molecular orbital basis. Molecular orbital densities are decomposed into a distribution of spherical components that conserve the charge and each of the interacting components is considered as a two-electron wavefunction embedded in the system acted on by an average field Hamiltonian plus 1 12 − r . A method of avoiding redundancy is described. Applications to atoms, negative ions and molecules representing different types of bonding and spin states are discussed.

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Configuration-interaction study of atoms. I. Correlation energies of B, C, N, O, F, and Ne

Cited by 174 publications

References 16 publications

Accurate elastic scattering factors for lithium to argon based on correlated wavefunctions

Accurate elastic scattering factors for lithium to argon based on correlated wavefunctions

Selected configuration interaction with truncation energy error and application to the Ne atom

Electron correlation by polarization of interacting densities

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