STRUCTURE AND PROPERTIES OF DISILYNE

The ground state of disilyne, Si2H2, has been studied using state of t he art methodology. In particular a quartic force field has been deter mined at the self-consistent field level, and the geometry has been op timized with large basis sets at the Moller-Plesset second order level , at the Brueckner doubles coupled cluster level and with Kohn-Sham de nsity functional theory. Our best calculations give excellent agreemen t with observed data for the rotational constants. The very intense nu 3 mode is predicted to lie near 1090 cm-1.