Automatic generation of analytical matrix elements for electron-atom scattering Original Research Article

A code which can be used to automatically generate entire sets of analytical matrix elements of the instantaneous electrostatic interaction potential between the projectile electron and the target atom is described. The code can be used at present for both hydrogen and helium target atoms. In the case of hydrogen, the present code Vij generalizes and extends an earlier code of Jamison [1]; while in the case of helium, Hartree-Fock frozen-core wave-functions are used to represent the two-electron wavefunctions. When an entire set of matrix elements is generated, a complete set of FORTRAN subroutines is produced which can be directly incorporated into the code MET_cross used to solve the multichannel eikonal theory (see accompanying paper). A principal application of the code Vij is to aid the elucidation of the systematic trends observed in transitions among metastable states in electron-atom collisions by studying the functional form of the underlying interaction matrix elements.