Pair Potential with Submillikelvin Uncertainties and Nonadiabatic Treatment of the Halo State of the Helium Dimer

Michał Przybytek, Wojciech Cencek, Bogumił Jeziorski, and Krzysztof Szalewicz

Phys. Rev. Lett. 119, 123401 – Published 21 September 2017

Abstract

The pair potential for helium is computed with accuracy improved by an order of magnitude relative to the best previous determination. For the well region, its uncertainties are now below 1 millikelvin. The main improvement is due to the use of explicitly correlated wave functions at the nonrelativistic Born-Oppenheimer (BO) level of theory. The diagonal BO and the relativistic corrections are obtained from large full configuration interaction calculations. Nonadiabatic perturbation theory is used to predict the properties of the halo state of the helium dimer. Its binding energy and the average value of the interatomic distance are found to be 138.9(5) neV and 47.13(8) Å. The binding energy agrees with its first experimental determination of 151.9(13.3) neV [Zeller et al., Proc. Natl. Acad. Sci. U.S.A. 113, 14651 (2016)].

Received 18 June 2017

DOI:https://doi.org/10.1103/PhysRevLett.119.123401

Physics Subject Headings (PhySH)

Electronic structure of atoms & molecules Interatomic & molecular potentials Long-range interactions Relativistic & quantum electrodynamic effects in atoms, molecules,& ions Van der Waals interaction

Density functional theory development First-principles calculations Quantum chemistry methods

Atomic, Molecular & Optical

Authors & Affiliations

Michał Przybytek^1,*, Wojciech Cencek², Bogumił Jeziorski¹, and Krzysztof Szalewicz²

¹Department of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland
²Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716, USA