Proceedings of the Royal Society of London A Mathematical and Physical Sciences

On the perturbation theory of small disturbances

A. Dalgarno, A L Stewart

Published Dec 18, 1956• 164 citations

Abstract

Abstract As a preliminary to a wide range of applications, conventional perturbation theory is re-examined and a number of useful properties emphasized. It is shown in particular that the total, kinetic and potential energies can be obtained to the (2s + 1)th order from a knowledge of only the sth-order wave function and that similar though less powerful theorems hold for other diagonal matrix elements. A combination of variational and perturbation techniques is suggested as the best method of calculating small disturbances of a stationary system.

DOI: 10.1098/rspa.1956.0219

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