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

► The highest level ab initio (MR-AQCC) calculations concerning the n−4s and n−4pe states of the CF3Cl have been performed. ► The effect of excluding the Cl L shell from frozen core space is studied. ► There are no previous results concerning the oscillator strength for the ground state → n−4pe transition.