RAPID RELATIVISTIC DISTORTED-WAVE APPROACH FOR CALCULATING CROSS-SECTIONS FOR IONIZATION OF HIGHLY CHARGED IONS

The rapid relativistic distorted-wave method of Zhang, Sampson, and Mohanty [Phys. Rev. A 40, 616 (1989)] for excitation, which uses the atomic-structure data of Sampson et al. [Phys. Rev. A 40, 604 (1989)], has been extended to ionization. In this approach the same Dirac-Fock-Slater potential evaluated using a single mean configuration is used in calculating the orbitals of all electrons bound and free. Values for the cross sections Q for ionization of various ions have been calculated, and generally good agreement is obtained with other recent relativistic calculations. When results are expressed in terms of the reduced ionization cross section QR, which is proportional to I2Q, they are close to the nonrelativistic Coulomb-Born-exchange values of Moores, Golden, and Sampson [J. Phys. B 13, 385 (1980)] for hydrogenic ions except for high Z and/or high energies. This suggests that fits of the QR to simple functions of the impact electron energy in threshold units with coefficients that are quite slowly varying functions of an effective Z can probably be made. This would be convenient for plasma-modeling applications. © 1990 The American Physical Society.