EGAS41 - Swansea University

41 st EGAS CP 202 Gdańsk 2009
Very accurate quantum calculations of vibrational transition
energies in diatomic systems
M. Stanke 1,∗ , L. Adamowicz 2
1 Nicholas Copernicus University, ul. Grudziadzka 5, PL 87-100 Torum, Poland
2 Department of Chemistry, University of Arizona, Tucson, Arizona 85721
∗ Corresponding author: monika@fizyka.umk.pl
Very accurate variational calculations of the pure vibrational transitions of some two- and
three-electron diatomic molecules have been performed within the framework that does
not assume the Born-Oppenheimer (BO) approximation. The non-BO wave functions
expanded in terms of one-center explicitly correlated Gaussian functions multiplied by
even powers of the internuclear distance are used to calculate the leading relativistic
corrections. Up to 10000 Gaussians are used for each state. We show that such calculations
reproduce the experimental vibrational transitions with the accuracy better than 0.1 cm −1 .
For three-electron systems this is the first time such an accuracy is reached in calculations
based on first principles.
References
[1] M. Stanke, S. Bubin, M. Molski, L. Adamowicz, Phys. Rev. A 79, 032507 (2009)
[2] M. Stanke, J. Komasa, D. Kedziera, S. Bubin, L. Adamowicz, Phys. Rev. A 78,
052507 (2008)
[3] M. Stanke, D. Kedziera, S. Bubin, L. Adamowicz, Phys. Rev. A 77, 022506 (2008)
[4] M. Stanke, D. Kedziera, S. Bubin, L. Adamowicz, Journal of Chemical Physics 128,
114313 (2008)
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