  High resolution measurements of photoionization cross sections for atomic
ions are now being made on synchrotron radiation sources. The recent
measurements by Kjeldsen etal. (1999) showed good agreement between the
observed resonance features and the the theoretical calculations in the close
coupling approximation (Nahar 1995). However, there were several observed
resonances that were missing in the theoretical predictions. The earlier
theoretical calculation was carried out in LS coupling where the relativistic
effects were not included. Present work reports photoionization cross sections
including the relativistic effects in Breit-Pauli R-matrix (BPRM)
approximation. The configuration interaction eigenfunction expansion for the
core ion C III consists of 20 fine structure levels dominated by the
configurations from 1s^22s^2 to 1s^22s3d. Detailed features in the calculated
cross sections exhibit the missing resonances due to fine structure. The
results benchmark the accuracy of BPRM photoionization cross sections as needed
for recent and ongoing experiments.
