The confined helium atom: An information–theoretic approach Estañón, C. R. Montgomery Jr., H. E. Angulo Ibáñez, Juan Carlos Aquino, Norberto Confined helium atom Disequilibrium Fisher information In this article, we study the helium atom confined in a spherical impenetrable cavity by using informational measures. We use the Ritz variational method to obtain the energies and wave functions of the confined helium atom as a function of the cavity radius r0. As trial wave functions we use one uncorrelated function and five explicitly correlated basis sets in Hylleraas coordinates with different degrees of electronic correlation. We computed the Shannon entropy, Fisher information, Kullback–Leibler entropy, Tsallis entropy, disequilibrium and Fisher–Shannon complexity, as a function of r0. We found that these entropic measures are sensitive to electronic correlation and can be used to measure it. As expected these entropic measures are less sensitive to electron correlation in the strong confinement regime (r0 < 1 a.u.). 2024-05-14T08:35:13Z 2024-05-14T08:35:13Z 2024-02-09 journal article C. R. Estañ on, H. E. Montgomery Jr., J. C. Angulo, N. Aquino, Int. J. Quantum Chem. 2024, 124(4), e27358. https://doi.org/10.1002/qua.27358 https://hdl.handle.net/10481/91746 10.1002/qua.27358 eng http://creativecommons.org/licenses/by-nc-nd/4.0/ open access Attribution-NonCommercial-NoDerivatives 4.0 Internacional John Wiley & Sons