Ab initio Calculations of the Strustures and Vibrational Freqencies of Cyclic Sulf-polyynes and Oxy-polyynes

At HF/6-31G^* level, the optimized geometries, the electronic structures, the total energies and the populations of cyclic sulf-polyynes and oxy-polyynes molecules (C₄O₂, C₄S₂, C₆S₂, C₆O₂, C₈O₂, C₈S₂, C₆O₃, C₆S₃ and C₉O₂, C₉S₂, C₁₇O₂, C₁₇S₂ are calculated. The stabities of above cyclic compounds have been discussed.