Two-Electron Atoms. IV. Some Sixth-Order Expectation Values

Abstract

The sixth‐order perturbation ground‐state wavefunction for two electrons about a nucleus of charge Z obtained in Paper III of this series is used to compute perturbation expectation expansion coefficients 〈Ω〉_p for 34 operators Ω through p = 6 where the total expectation value of an operator 〈Ω〉 is given by 〈Ω〉 = Σ_pZ^—p〈Ω〉_p in appropriate units. Estimates of the accuracy of the calculation are obtained by comparison with exactly known values, by comparison with total values obtained from the accurate variational calculations of Pekeris, and by comparison with calculations based on Eqs. (V.1) and (V.2) of Paper III of this series. The function of the higher order correction terms is discussed.