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Skrzyński G, Musial M. Benchmark Study of the Electronic States of the LiRb Molecule: Ab Initio Calculations with the Fock Space Coupled Cluster Approach. Molecules 2023; 28:7645. [PMID: 38005367 PMCID: PMC10675596 DOI: 10.3390/molecules28227645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 10/27/2023] [Accepted: 11/14/2023] [Indexed: 11/26/2023] Open
Abstract
Accurate potential energy curves (PECs) are determined for the twenty-two electronic states of LiRb. In contrast to previous studies, the applied approach relies on the first principle calculations involving correlation among all electrons. The current methodology is founded on the multireference coupled cluster (CC) scheme constructed within the Fock space (FS) formalism, specifically for the (2,0) sector. The FS methodology is established within the framework of the intermediate Hamiltonian formalism and offers an intruder-free, efficient computational scheme. This method has a distinctive feature that, when applied to the doubly ionized system, provides the characteristics of the neutral case. This proves especially beneficial when investigating PECs in situations where a closed-shell molecule dissociates into open-shell fragments, yet its double positive ion forms closed-shell species. In every instance, we successfully computed continuous PECs spanning the entire range of interatomic distances, from the equilibrium to the dissociation limit. Moreover, the spectroscopic characteristic of various electronic states is presented, including relativistic effects. Relativistic corrections included at the third-order Douglas-Kroll level have a non-negligible effect on the accuracy of the determined spectroscopic constants.
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Affiliation(s)
- Grzegorz Skrzyński
- Institute of Chemistry, University of Silesia in Katowice, Szkolna 9, 40-006 Katowice, Poland
| | - Monika Musial
- Institute of Chemistry, University of Silesia in Katowice, Szkolna 9, 40-006 Katowice, Poland
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Bormotova EA, Kozlov SV, Pazyuk EA, Stolyarov AV, Majewska I, Moszynski R. Theoretical study of the Coriolis effect in LiNa, LiK, and LiRb molecules. Phys Chem Chem Phys 2021; 23:5187-5198. [PMID: 33624674 DOI: 10.1039/d0cp06487d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The non-adiabatic electronic matrix elements, LΠΣ(R), that arise from the spin-conserving electron-rotational interactions between all mΣ+ and mΠ states, where multiplicity m = 1, 3, converging to the lowest three dissociation limits of Li-containing alkali diatomics, LiM (M = Na, K, Rb), were calculated ab initio up to large internuclear distances, R. The required electronic wavefunctions were obtained within the framework of the multi-reference configuration interaction treatment of the two-valence-electron problem constructed using small-core scalar-relativistic effective core potentials and l-independent core-polarization potentials. A least squares analysis of the ab initio functions at large internuclear distances in conjunction with long-range perturbation theory (LRPT) revealed three different asymptotic behaviors of the LΠΣ(R → +∞)-functions: const. + β[n]/Rn, characterized by n = -1, 3 and 6. The asymptotic coefficients β[n], extracted from the point-wise ab initio data, were found to be in agreement with their LRPT counterparts, which were evaluated analytically using the relevant atomic parameters. The mass dependence of the LΠΣ matrix elements was investigated analytically and numerically. To confirm the reliability of the LΠΣ(R)-functions and interatomic potentials at small and intermediate distances, the empirical q-factors available for the D1Π-states of all LiM molecules studied were compared with their theoretical counterparts derived from the present ab initio data.
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Affiliation(s)
- E A Bormotova
- Department of Chemistry, Lomonosov Moscow State University, Leninskie gory 1/3, 119991, Moscow, Russia.
| | - S V Kozlov
- Department of Chemistry, Lomonosov Moscow State University, Leninskie gory 1/3, 119991, Moscow, Russia.
| | - E A Pazyuk
- Department of Chemistry, Lomonosov Moscow State University, Leninskie gory 1/3, 119991, Moscow, Russia.
| | - A V Stolyarov
- Department of Chemistry, Lomonosov Moscow State University, Leninskie gory 1/3, 119991, Moscow, Russia.
| | - I Majewska
- Quantum Chemistry Laboratory, Department of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland.
| | - R Moszynski
- Quantum Chemistry Laboratory, Department of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland.
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Ab initio study of R-dependent behavior of the hyperfine structure parameters for the (1)1,3Σ+ states of LiRb and LiCs. Chem Phys Lett 2020. [DOI: 10.1016/j.cplett.2020.137998] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Oleynichenko AV, Zaitsevskii A, Eliav E. Towards High Performance Relativistic Electronic Structure Modelling: The EXP-T Program Package. COMMUNICATIONS IN COMPUTER AND INFORMATION SCIENCE 2020. [DOI: 10.1007/978-3-030-64616-5_33] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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