Chinese Physics Letters
Normally Ordered Expansion of the Even-Power of the Radial Coordinate Operator
Fan Hong‐Yi
Abstract
By virtue of the technique of integration within an ordered product of operators we derive the concise normally ordered expansion of the even-power of the radial coordinate operator via the equation = ∫ d 3 x | x ⟩⟨ x | r , where | x ⟩ is the three-dimensional coordinate eigenvector, and r = ( x 2 + y 2 + z 2 ) 1/2 . The application to perturbation theory is briefly discussed.