HSTERM - A PROGRAM TO CALCULATE POTENTIAL CURVES AND RADIAL MATRIX-ELEMENTS FOR 2-ELECTRON SYSTEMS WITHIN THE HYPERSPHERICAL ADIABATIC APPROACH

A FORTRAN 77 program is presented which calculates potential curves an d matrix elements of radial coupling for two-electron systems using th e hyperspherical coordinate method. The adiabatic and diabatic-by-sect or close-coupling approaches are considered, The program calculates al so the overlap matrices on borders of all sectors which are necessary for integration of close-coupling hyperradial equations within the sec tor-diabatic approach. It performs also the computation of the angular part of dipole amplitudes (in the length and acceleration forms) for dipole transitions between two given atomic states. The convergence an d accuracy of the computational scheme elaborated are studied in detai ls. Radial matrix elements computed by the HSTERM program can be used for the solution of the bound state and scattering problems for two-el ectron systems in both the adiabatic and diabatic-by-sector close-coup ling approaches.