Time-dependent close-coupling calculations of correlated photoionization processes in helium

Various correlated photoionization processes in helium are calculated by direct solution of the time-dependent Schrödinger equation. An inhomogeneous set of time-dependent close-coupled partial differential equations are partitioned on a numerical lattice for easy implementation on massively parallel computers. Projection of the time evolved wave function onto lattice eigenstates for ${\mathrm{He}}^{+}$ yields cross sections for photoionization with excitation and double photoionization. The computational results are compared with recent experimental measurements.