Relativistic multireference Møller–Plesset perturbation theory based on multiconfigurational Dirac–Fock reference functions

Vilkas, Marius J.; Koc, Konrad; Ishikawa, Yasuyuki

doi:10.1016/s0009-2614(98)00983-x

Cited by 22 publications

(13 citation statements)

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“…Benchmark calculations on the U͑IV͒ ion were done using the radial relativistic Fock space CC code of Eliav et al 24 and the multi-reference Møller-Plesset ͑MR-MP͒ code of Vilkas et al [43][44][45] for the CASPT2 calculations. All-electron single-and multireference correlated calculations on the UO 2 molecule were carried out utilizing a locally modified version of the DIRAC04 program.…”

Section: Methodsmentioning

confidence: 99%

“…Further increase of the model space was not possible, because it leads to intruder states, in particular, in sector ͑0,2͒. The CASPT2 approach [43][44][45] used in some of the atomic reference calculations is similar, but not identical to the method used by Gagliardi et al in calculations of the UO 2 molecule. 18 The main difference is in construction of one-electronic orbital space.…”

Section: Methodsmentioning

confidence: 99%

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A Fock space coupled cluster study on the electronic structure of the UO2, UO2+, U4+, and U5+ species

Infante

Eliav

Vilkas

et al. 2007

The Journal of Chemical Physics

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137

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The ground and excited states of the UO 2 molecule have been studied using a Dirac-Coulomb intermediate Hamiltonian Fock-space coupled cluster approach ͑DC-IHFSCC͒. This method is unique in describing dynamic and nondynamic correlation energies at relatively low computational cost. Spin-orbit coupling effects have been fully included by utilizing the four-component Dirac-Coulomb Hamiltonian from the outset. Complementary calculations on the ionized systems UO 2 + and UO 2 2+ as well as on the ions U 4+ and U 5+ were performed to assess the accuracy of this method. The latter calculations improve upon previously published theoretical work. Our calculations confirm the assignment of the ground state of the UO 2 molecule as a 3 ⌽ 2u state that arises from the 5f 1 7s 1 configuration. The first state from the 5f 2 configuration is found above 10 000 cm −1 , whereas the first state from the 5f 1 6d 1 configuration is found at 5 047 cm −1 .

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

A Fock space coupled cluster study on the electronic structure of the UO2, UO2+, U4+, and U5+ species

Infante

Eliav

Vilkas

et al. 2007

The Journal of Chemical Physics

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137

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“…Froese Fischer et al (1998) the used multiconfiguration Dirac-Hartree-Fock (MCDHF) method to calculate transition rates for the 2s 2 2p 4 3 P 1,2 − 2s 2 2p 3 3s 5 S o 2 and 2s 2 2p 4 3 P 1,2 −2s2p 5 3 P o 2 transitions in the oxygen-like ions for Z = 9-18. Vilkas et al (1998Vilkas et al ( , 1999 used multireference Møller-Plesset (MRMP) perturbation theory for the ground and low-lying excited states of oxygen-like iron and oxygen-like ions with nuclear charge up to Z = 60. No transition data were published.…”

Section: Introductionmentioning

confidence: 99%

Energies and E1, M1, E2, and M2 transition rates for states of the 2s²2p⁴, 2s2p⁵, and 2p⁶configurations in oxygen-like ions between F II and Kr XXIX

Rynkun

Jönsson

Gaigalas

et al. 2013

A&A

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Based on relativistic wave functions from multiconfiguration Dirac-Hartree-Fock and configuration interaction calculations, E1, M1, E2, M2 transition rates, weighted oscillator strengths, and lifetimes are evaluated for the states of the (1s 2 )2s 2 2p 4 , 2s2p 5 , and 2p 6 configurations in all oxygen-like ions between F II and Kr XXIX. Valence and core-valence correlation effects were accounted for through single-double multireference (SD-MR) expansions to increasing sets of active orbitals. Computed energies are compared with the NIST recommended values, generally differing by less than 600 cm −1 . For some spectra, significantly larger differences are found and our results are in better agreement with Edlén interpolated values. For levels where experimental lifetimes are available, the agreement is within experimental uncertainty for all but a few lowly ionized spectra. Complete Online tables of energy levels and transition data are available.

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“…Both single and double excitations are allowed to 15 The matrix elements of the allowed E1 transitions changed at most by 0.06%. Therefore, the basis set is numerically complete and the CI space is sufficiently saturated in our example.…”

Section: Basis Setmentioning

confidence: 99%

“…Relativistic multireference Møller-Plesset perturbation theory was developed and implemented with analytic basis sets of Gaussian spinors in [15].…”

Section: Introductionmentioning

confidence: 99%

CI-MBPT: A package of programs for relativistic atomic calculations based on a method combining configuration interaction and many-body perturbation theory

Kozlov

Porsev

Safronova

et al. 2015

Computer Physics Communications

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a b s t r a c tThis package of programs allows us to carry out relativistic calculations for many-electron atoms and ions. One can find energy levels and a number of atomic properties: g-factors, magnetic-dipole and electricquadrupole hyperfine structure constants, electric-and magnetic-multipole transition amplitudes, and matrix elements of the parity nonconserving interactions. Method of calculation is based on a combination of conventional configuration interaction (CI) method and many-body perturbation theory (MBPT). The former explicitly accounts for the interaction between valence electrons, while the latter includes core-core and core-valence correlations. These two methods are combined to acquire benefits from both approaches and attain better accuracy. Program summary Program title: CI-MBPT Catalogue identifier: AEWV_v1_0Program summary URL: Nature of problem: Prediction of atomic or ionic energy levels and different observables in the framework of relativistic approach. Solution method: The package of programs determines energy levels and associated many-electron wave functions for states of atoms and ions in the pure CI or CI + MBPT approximations. Using the wave functions, different atomic properties can be obtained, including g-factors, magnetic-dipole and ✩ This paper and its associated computer program are available via the Computer Physics Communication homepage on ScienceDirect (S.G. Porsev). http://dx.doi.org/10.1016/j.cpc.2015.05.007 0010-4655/© 2015 Elsevier B.V. All rights reserved.2 M.G. Kozlov et al. / Computer Physics Communications ( ) -electric-quadrupole hyperfine structure constants, electric-and magnetic-multipole transition amplitudes, P-odd and P,T-odd amplitudes.Restrictions: The package is not designed for calculations of high Rydberg and autoionizing states. It becomes inefficient for the number of valence electrons exceeding four or five. It has not been tested for superheavy elements. The maximal number of Hartree-Fock-Dirac (HFD) orbitals when HFD equations are solved is 32.Unusual features: One-electron orbitals outside the nucleus are defined on radial grid points. Inside the nucleus they are described in a form of the Taylor expansion over r/R, where R is the nuclear radius.Additional comments: All programs have been compiled, linked, and tested with both ''ifort'' and freely available ''gfortran''.Running time: Changes from tens of minutes for atoms with two valence electrons to tens of hours for more complex systems.

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Relativistic multireference Møller–Plesset perturbation theory based on multiconfigurational Dirac–Fock reference functions

Cited by 22 publications

References 24 publications

A Fock space coupled cluster study on the electronic structure of the UO2, UO2+, U4+, and U5+ species

A Fock space coupled cluster study on the electronic structure of the UO2, UO2+, U4+, and U5+ species

Energies and E1, M1, E2, and M2 transition rates for states of the 2s²2p⁴, 2s2p⁵, and 2p⁶configurations in oxygen-like ions between F II and Kr XXIX

CI-MBPT: A package of programs for relativistic atomic calculations based on a method combining configuration interaction and many-body perturbation theory

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Relativistic multireference Møller–Plesset perturbation theory based on multiconfigurational Dirac–Fock reference functions

Cited by 22 publications

References 24 publications

A Fock space coupled cluster study on the electronic structure of the UO2, UO2+, U4+, and U5+ species

A Fock space coupled cluster study on the electronic structure of the UO2, UO2+, U4+, and U5+ species

Energies and E1, M1, E2, and M2 transition rates for states of the 2s22p4, 2s2p5, and 2p6configurations in oxygen-like ions between F II and Kr XXIX

CI-MBPT: A package of programs for relativistic atomic calculations based on a method combining configuration interaction and many-body perturbation theory

Contact Info

Product

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Energies and E1, M1, E2, and M2 transition rates for states of the 2s²2p⁴, 2s2p⁵, and 2p⁶configurations in oxygen-like ions between F II and Kr XXIX