Abstract
Analytical expressions for the matrix elements 〈vJ‖(r-re )lexp[-ma(r-re) ]‖vJ〉 of a rotating Morse oscillator are obtained, where l is a non-negative integer and m is any number. These matrix elements are also obtained by a recursive method that obviates the need for using explicit eigenfunctions. This procedure is based on the hypervirial theorem together with the second-quantization formalism. The results permit the diagonal (v=v,J=J) and off-diagonal (v≠v,J=J) matrix elements of the operator (r-re )l to be calculated.