Molecular Structure Theory without the Born-Oppenheimer Approximation: Rotationless Vibrational States of LiH
Nasiri S. Bubin S. Stanke M. Adamowicz L.
24 October 2024American Chemical Society
Journal of Physical Chemistry A
2024#128Issue 429175 - 9183 pp.
Low-lying rotationless states of the lithium hydride molecule are studied in the framework of the variational method without assuming the Born-Oppenheimer (BO) approximation. Highly accurate solutions to the six-particle (two nuclei and four electrons) Schrödinger equation are obtained by means of expanding the wave functions of the considered states in terms of many thousands of all-particle explicitly correlated Gausssians. The basis functions are optimized independently for each state using the analytic energy gradient with respect to the nonlinear parameters. The non-BO wave functions obtained in the calculations are used to evaluate the leading-order relativistic and quantum electrodynamics energy corrections in the framework of the perturbation theory. The geometric structure of the molecule in the ground and excited states is discussed based on the analysis of the nucleus-nucleus correlation functions. The non-BO energies and structural parameters obtained of this work are compared with the most accurate BO results currently available.
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Department of Physics, Nazarbayev University, Astana, 010000, Kazakhstan
Institute of Physics, Faculty of Physics, Astronomy, and Informatics, Nicolaus Copernicus University, ul. Grudziądzka 5, Toruń, PL 87-100, Poland
Department of Chemistry and Biochemistry, University of Arizona, Tucson, 85721, AZ, United States
Department of Physics, University of Arizona, Tucson, 85721, AZ, United States
Department of Physics
Institute of Physics
Department of Chemistry and Biochemistry
Department of Physics
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