AbstractThe effect of polarization functions forab initiomolecular orbital calculations at the 3‐21G* level has been studied for disiloxane. Calculated molecular geometry, dipole moment, and the linearization barrier variation were analyzed for different uncontracted polarization functions. It was concluded that variation of the polarization function on oxygen has only a minor influence on the molecular properties of disiloxane, but its presence is required to obtain a bent geometry for the disiloxane bond. The calculated molecular properties of disiloxane are greatly influenced when the polarization function on silicon is varied. Two different values (0.3 and 0.9) for the exponent of the silicon polarization function provide results comparable to the experimental values for disiloxane. The only significant differences between the results obtained fromab initiocalculations using the two polarization functions are in net atomic charges. The uncontracted polarization function of silicon with a value of 0.3 for its exponent is transferable to other organosilicon compounds. Calculated molecular geometries of flexible or rigid structures are in very good agreement with the experimental value