Z-expansion of matrix elements of one-electron operators for many-electron atoms

Program SSTR (Substitution Sums for Transitions), computes the generalized single-particle substitution sums used in obtaining the coefficient of the second term in the Z-expansion of the matrix elements of one-electron operators in many-electron atoms. The calculations correspond in complexity to those needed for the contributions E'2 in the second-order energy, but not to those needed for E''2. The program is generalized to use one-electron operators corresponding to rsup(kk), for brevity referred to as a 'transition', from a state with quantum numbers n1l1 to state n2l2 in the presence of the n0l0 core electron. (Auth.)