ABSTRACT:Evidence is given on the usefulness of the variational method to explore the nonseparable Schroedinger problem for the energy evolution of one-electron atoms and diatomic molecular ions confined by a hard prolate spheroidal cavity when the nuclear positions do not coincide with the foci. In this work, we study explicity the case of the hydrogen atom (H) and the H 2 ϩ and HeH ϩϩ under the aforementioned confinement conditions and obtain variationally the energy evolution as a function of nuclear positions along the major axis of a confining spheroid of fixed size and eccentricity. The particular case of an electron (e Ϫ ) under the same confinement conditions is also addressed using the same methodology. Our calculations are restricted to the ground states of H (1s), HeH ϩϩ (1s), e Ϫ ͑1s͒ and the ground-state ͑1s g ) and first excited state (2p u ) of H 2 ϩ . It is shown that a simple LCAO Dickinsontype variational ansatz wavefunction adapted for the confinement case of all systems treated in this work provides very rewarding results for the energy dependence on the size and shape of the confining cavity when compared with corresponding available exact calculations. For e Ϫ as well as for H, H 2 ϩ and HeH ϩϩ with "on-focus" nuclear positions excellent general quantitative agreement is observed. For the "off-focus" case, moderate quantitative agreement is obtained with available accurate B-spline variational calculations for H. For the molecular systems with "off-focus" nuclear positions, the results of this work are the first of this kind.