Accurate spectroscopic properties by diffusion quantum Monte Carlo calculations.

Autor: Carvalho CMC; Institute of Chemistry, University of Brasília, Campus Darcy Ribeiro, Brasília, DF, Brazil., Gargano R; Institute of Physics, University of Brasília, Campus Darcy Ribeiro, Brasília, DF, Brazil., Martins JBL; Institute of Chemistry, University of Brasília, Campus Darcy Ribeiro, Brasília, DF, Brazil., Politi JRS; Institute of Chemistry, University of Brasília, Campus Darcy Ribeiro, Brasília, DF, Brazil. Electronic address: politi@unb.br.
Jazyk: angličtina
Zdroj: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy [Spectrochim Acta A Mol Biomol Spectrosc] 2020 Dec 15; Vol. 243, pp. 118707. Date of Electronic Publication: 2020 Jul 30.
DOI: 10.1016/j.saa.2020.118707
Abstrakt: The capability of Diffusion Quantum Monte Carlo (DMC) to produce high quality potential energy curve (PEC) was evaluated. H 2 + , HeH + and LiH PECs were built by all-electron fixed-node DMC calculations. Trial wave functions were obtained from Hartree-Fock (HF) (H 2 + ), MCSCF and CI (HeH + and LiH) calculations multiplied by Jastrow factor. The quality of these generated PECs was analyzed throughout equilibrium distance, dissociation energy, vibrational energies and rovibrational spectroscopic constants (ω e , ω e x e , ω e y e , α e , γ e and B e ). The Discrete Variable Representation (DVR) and the Dunham approaches were used to determine the rovibrational spectroscopic constants. The PECs and the aforementioned properties were also obtained by the following methods: MCSCF/aug-cc-pV5Z (LiH), CCSD(T)/aug-cc-pV5Z (HeH + and LiH) and HF (H 2 + and HeH + ) levels. The results of these DMC computations, specially the DMC-DVR procedure, are the most accurate among others DMC calculations available in the literature for these systems. They suggest that DMC can be used to achieve accurate PECs to produce spectroscopic properties with the same level of accuracy of theoretical benchmarks and experimental data of the literature.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2020 Elsevier B.V. All rights reserved.)
Databáze: MEDLINE
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