[en] A preliminary report is presented on the effect of correlation in the 3d/sup n/ core on the 3d¹⁰¹S → 3d⁹ 4p ¹P f value by use of the multiconfiguration (MC) Hartree-Fock procedure. A common orbital basis was used for correlation in the core, with virtual orbitals determined variationally for the initial state. Three different approximations were used: a single-configuration approximation for both initial and final state, a MC approximation for 3d¹⁰ correlation in the initial state and a single configuration for the final state, and MC approximations for both initial and final states. Some preliminary f values for the 3d¹⁰¹S → 3d⁹ 4p ¹P transition are tabulated. Comparison of calculated with experimental values indicates that correlation in the 3d⁹ core of the final state is needed to obtain the correct transition energy to bring the length and velocity forms into good agreement with themselves and experiment, and that the multiplet strength for the transition is not greatly affected by correlation. 1 table