Configuration Interaction Study of the  3 P Ground State of the Carbon Atom

Ruiz, María Belén; Tröger, Robert

doi:10.1016/bs.aiq.2017.07.001

Cited by 6 publications

(3 citation statements)

References 24 publications

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“…There has been a number of accurate total energy studies for all-electron atoms using a variety of methods such as coupled cluster, DMC with multi-determinant nodes, FCI, etc (see references [31][32][33][34] for selected cases). However, rigorous examinations of ECP total energies have been rather sporadic and in many cases, only finite basis and limited accuracy methods were employed.…”

Section: Discussionmentioning

confidence: 99%

Accurate Atomic Correlation and Total Energies for Correlation Consistent Effective Core Potentials

Annaberdiyev

Melton

Bennett

et al. 2020

J. Chem. Theory Comput.

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Very recently, we introduced a set of correlation consistent effective core potentials (ccECPs) constructed within full many-body approaches. By employing significantly more accurate correlated approaches we were able to reach a new level of accuracy for the resulting effective core Hamiltonians. We also strived for simplicity of use and easy transferability into a variety of electronic structure methods in quantum chemistry and condensed matter physics. Here, as a reference for future use, we present exact or nearlyexact total energy calculations for these ccECPs. The calculations cover H-Kr elements and are based on the state-of-the-art configuration interaction (CI), coupled-cluster (CC), and quantum Monte Carlo (QMC) calculations with systematically eliminated/improved errors. In particular, we carry out full CI/CCSD(T)/CCSDT(Q) calculations with cc-pVnZ with up to n=6 basis sets and we estimate the complete basis set limits. Using combinations of these approaches, we achieved an accuracy of ≈ 1-10 mHa for K-Zn atoms and ≈ 0.1-0.3 mHa for all other elements − within about 1% or better of the ccECP total correlation energies. We also estimate the corresponding kinetic energies within the feasible limit of full CI calculations. In order to provide data for QMC calculations, we include fixed-node diffusion Monte Carlo energies for each element that give quantitative insights into the fixed-node biases for single-reference trial wave functions. The results offer a clear benchmark for future high accuracy calculations in a broad variety of correlated wave function methods such as CI and CC as well is in stochastic approaches such as real space sampling QMC. arXiv:1909.12453v1 [cond-mat.mtrl-sci]

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Section: Discussionmentioning

confidence: 99%

Accurate Atomic Correlation and Total Energies for Correlation Consistent Effective Core Potentials

Annaberdiyev

Melton

Bennett

et al. 2020

J. Chem. Theory Comput.

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“…are calculated as expectation values of respective operators, with known nonrelativistic wavefunction. E (0) is the nonrelativistic energy, E (2) contains the Breit-Pauli corrections and higher order terms are the QED (radiative) corrections. The Breit-Pauli Hamiltonian contains the ĤRS operator, which is responsible for the scalar relativistic correction, shifting the energies of whole terms, and the fine and hyperfine structure operators.…”

Section: B Relativistic Correctionsmentioning

confidence: 99%

“…That result still represents the most accurate published CI energy of this state. Recent CI calculation in which configurations were selected carefully, considering their energy contributions, but built from orbitals the with l limited to 4, gave a little higher energy [2]. Comparison with the work devoted to boron atom and anion (the latter being isoelectronic with carbon atom's ground state) [3], makes it clear that orbitals with much higher l are needed for building a many-electron basis, capable of yielding the accuracy of about 1 mhartree.…”

Section: Introductionmentioning

confidence: 99%

Explicitly correlated wave functions of the ground state and the lowest quintuplet state of the carbon atom

Strasburger

2019

Phys. Rev. A

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Variational, nonrelativisitic energies have been calculated for the ground state ( 3 P g ) and the lowest quintuplet state ( 5 S u ) of the carbon atom, with wavefunctions expressed in the basis of symmetry-projected, explicitly correlated Gaussian (ECG) lobe functions. New exact limits of these energies have been estimated, amounting to −37.844906(4) and −37.691751(2) hartree. With finite nuclear masses and leading, scalar relativistic corrections included, respective experimental excitation energy of 12 C has been reproduced with accuracy of about 7 cm −1 .

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Spin states of the light atoms

Ruiz

2018

Rend. Fis. Acc. Lincei

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Configuration Interaction Study of the 3 P Ground State of the Carbon Atom

Cited by 6 publications

References 24 publications

Accurate Atomic Correlation and Total Energies for Correlation Consistent Effective Core Potentials

Accurate Atomic Correlation and Total Energies for Correlation Consistent Effective Core Potentials

Explicitly correlated wave functions of the ground state and the lowest quintuplet state of the carbon atom

Spin states of the light atoms

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