Cubic and quartic anharmonic potential energy functions for octahedral XY6 molecules

We give the cubic and quartic anharmonic potential energy functions for XY6 molecules of Oh symmetry in terms of normal coordinates. The numbers of independent cubic and quartic potential constants are 22 and 92, respectively. A standard form, introduced here, is related to the tensor formalism developed for the potential energy of tetrahedral XY4 molecules by Hecht.