Time-dependent calculations of double photoionization of the aligned H ₂ molecule

We perform time-dependent calculations of single-photon two-electron ionization of the aligned H ₂ molecule by an xuv pulse. Solution of the time-dependent Schrödinger equation is sought in spherical coordinates on a radial grid by time propagation using the Arnoldi-Lanczos method. From these calculations, we derive the total integrated as well as fully differential ionization cross sections for equal energy sharing and various orientations of the internuclear axis relative to the polarization vector of light. Satisfactory agreement with available literature data validates the present theoretical model. We supplement our numerical computations with an amplitude analysis of differential cross sections using the atomiclike formalism of Feagin. This analysis provides some additional insight into mechanisms of double photoionization of the aligned H ₂ molecule.