Many-electron atom confinement by a penetrable prolate spheroidal cavityS. A. Cruz, C. Díaz-García, D. Garrido-Aguirre and R. Reyes-GarcíaEur. Phys. J. D, 75 4 (2021) 143DOI: https://doi.org/10.1140/epjd/s10053-021-00150-3