Energy spectra of three‐dimensional harmonium under Debye potential obtained using the shifted 1/N expansion approach

In this work, the problem of harmonium was investigated using the method of the shifted 1/N expansion. The energy eigenvalues and the classical equilibrium interelectron distance were calculated for ground and few first excited states under Debye potential as a function of both the Debye screening length and the harmonic confinement strength. It was found that harmonium becomes a Wigner molecule at the strong‐correlation limit in which the two electrons oscillate about the classical equilibrium interelectron distance r₀ . The results show reasonable agreement with the previous results both quantitatively and qualitatively.