Double-continuum R-matrix theory and codes for many-electron atoms: ionizing electron collisions and time-dependent laser-induced double-ionization

An extension of ab initio many-electron R-matrix theory is described which is relevant both to the time-dependent description of excitation and single and double ionization of atoms in laser pulses, and to time-independent calculation of intermediate energy electron collisions where ionized states of the target atom can be excited. Corresponding general many-electron 'inner region' code modules have been developed for use in combination with existing R-matrix method codes for diverse applications with up to two electrons explicitly described by a continuum orbital basis.