Energies of the αx3+ βx4anharmonic oscillator from a modified operator method

Abstract
Highly improved perturbation series for the anharmonic oscillator with potential V(x) = ½ω2 + αx 3 + βx 4 are obtained from a modified operator method consisting of an appropriate partitioning of the hamiltonian operator. Very accurate energy eigenvalues of various eigenstates are calculated for small α values. The present results compare favourably with results from the hypervirial-Padé approach.