A Fortran program to calculate the matrix elements of the Coulomb interaction involving hydrogenic wave functions Original Research Article

The presented program calculates the matrix elements of the Coulomb interaction between a charged particle and an atomic electron, ∫ψf∗(r) |R−r|−1ψi(r) dr. Bound-free transitions are considered, and non-relativistic hydrogenic wave functions are used. The program consists of subroutines that compute matrix elements between eigenstates of both the total angular momentum j, and the orbital angular momentum l. As further output quantities, the radial components of the multipole series expansion of the matrix elements (the so-called G functions) can be obtained, as well. The structure of the program is such that the hydrogenic wave functions can be replaced by arbitrary one-electron wave functions.