Pion-nucleus single-charge exchange to the isobaric analogue state in the energy region from 300 MeV to 500 MeV is investigated utilizing a microscopic, momentum-space, isospin invariant optical potential. The optical potential utilizes fully relativistic kinematics, and the Fermi integration is performed exactly. The model used for the pion-nucleus interaction includes a new model for the resonant D-waves. Our results are compared to recent data for 0 ° excitation functions for the isobaric analogue state transitions in 14C and 90Zr. The observed rise in the cross section for energies above the resonance is reproduced by the theory, and, although not totally quantitative, the theoretical results indicate that the multiple scattering theory as defined and implemented here is significantly more convergent at the higher energies than at or below the resonance.