We will begin in Section 2.1 by outlining how the high-order molecular properties used in this work can be calculated analytically through the use of our recently developed recursive response code and then in Section 2.2 proceed to show how these properties can be used to determine anharmonic corrections to vibrational frequencies and IR and Raman intensities. Although the general framework has been described previously,46–48 this work is the first report of fifth-order analytic derivatives involving geometrical distortions.