CASSCF and MR–CISD study of the n−4s and n−4pe Rydberg states of the CF3Cl

The low-lying n−4s (S2 and T2) and n−4pe (S3 and T3) Rydberg states of the CF3Cl have been studied at the CASSCF, MR–CISD, MR–CISD + Q and MR–AQCC levels using the mixed aug–cc–pVDZ/d–aug–cc–pVDZ and aug′–cc–pVTZ/d′–aug′–cc–pVTZ basis sets. Spin–orbit corrections for the singlet energies, vertical excitation energies and oscillator strengths have been computed. The effect of the inclusion of K + L or only the K inner shell chlorine orbitals in the frozen core space at the post-CASSCF levels has also been discussed. Good agreement with available experimental and with previous high-level theoretical results has been achieved.