Perturbative-variational calculations in two-well anharmonic oscillators

Abstract

The perturbative-variational method is used with a nonorthogonal basis set whose elements are combinations of two harmonic-oscillator functions symmetrically shifted around the origin in order to approximate the eigenvalues and eigenfunctions of the two-well anharmonic-oscillator potential [V(x)=-${\mathit{Z}}^{2}$${\mathit{x}}^{2}$+${\mathit{x}}^{4}$ with ${\mathit{Z}}^{2}$>0]. This basis set is rather adequate for this potential and allows one to calculate not only the ground-state energy but also the energy of the excited states with very high precision.