Hydrogen atom and one-electron molecular systems in a strong magnetic field: are all of them alike?

Easy physics-inspired approximations of the total and binding energies for the ${\rm H}$ atom and for the molecular ions $${\rm H}_2^{(+)} ({\rm ppe}), {\rm H}_3^{(2+)} ({\rm pppe}), ({\rm HeH})^{++} (\al {\rm p e}), {\rm He}_2^{(3+)} (\al \al {\rm e})$$ as well as quadrupole moment for the ${\rm H}$ atom and the equilibrium distances of the molecular ions in strong magnetic fields $> 10^{9}$ G are proposed. The idea of approximation is based on the assumption that the dynamics of the one-electron Coulomb system in a strong magnetic field is governed by the ratio of transverse to longitudinal sizes of the electronic cloud.