Relativistic coupled-channel calculations including pseudostates

The previously developed relativistic, two-center, coupled-channel treatment of atomic collisions between high-Z ions has been extended to include pseudostates. By augmenting the atomic basis sets by pseudostates, an approximate representation of the continuum is obtained as well as an improved description of quasimolecular states near the united-atom limit. The problems arising from approximate basis states, specifically in relativistic collisions, are discussed. Numerical calculations for ${\mathrm{U}}^{92+}$+${\mathrm{U}}^{91+}$ at 500 MeV/u are performed with basis sets of up to 36 real and 16 continuum pseudostates. While the presently attainable basis sets are presumably still too small, one can get, nevertheless, reasonable estimates of the cross sections for ionization and K-vacancy production.