Some inner product techniques for computing eigenvalues for three-dimensional anharmonic oscillators with quartic and sextic perturbations

An algorithm previously used by the author for calculating the energy eigenvalues for a three-dimensional oscillator with limited range of perturbation parameters, eigenstates and accuracy is revisited and implemented in a more effective way to give excellent accuracy even for higher values of λ and ψnx, ny, nz(x,y,z). Fifty coefficients of renormalized perturbation series are calculated, in contrast to the previous works which were limited to 20 coefficients of the perturbation series due to computational facilities. Some of the results calculated by the inner product technique are compared with results produced by other techniques.