AB-INITIO CALCULATIONS OF THE STRUCTURE AND PROPERTIES OF DISILOXANE - THE EFFECT OF ELECTRON CORRELATION AND BASIS-SET EXTENSION

Ab initio calculations on the SCF, MP2, CI(SD) and CPF level are presented for disiloxane. The convergence of the results is studied for a series of basis sets of increasing quality. Large basis sets including f functions are necessary to obtain reliable results for the structure and the barrier to linearization of this molecule. The following estimates are made: The SiO distance is (162.6 +/- 0.5) pm, the barrier to linearization is smaller than 150 cm-1 and the SiOSi angle is larger than 14 5-degrees.