ABINITIO CHARACTERIZATION OF GASEOUS P2O2

Ab initio electronic structure calculations demonstrate that a singlet planar cyclic isomer Of P2O2 with D2h symmetry is more stable than al l the previously characterized P2O2 isomers. A proper description of t he electronic structure wavefunction is found to be essential to predi ct correctly the multiplicity of the ground state. This singlet D2h sy mmetry isomer is found to have no central P-P bond and a large biradic al character.