Abstract :
An an initio investigation on the hypothetical systems CnOn (n = 2, 3, 4) is presented. Calculations have been performed at SCF and MP2 level, using a [3s2p1 d] basis set on each atom. At this level of approximation, two metastable structures have been found. They are C2O2 with C2v symmetry (an irregular tetrahedron) and C4O4 with Td symmetry (two regular tetrahedra copenetrating each other). On the other hand, the search of local minima with Cnv structures has failed for n = 3, 4. For the two metastable structures also larger basis sets have been used, up to [4s3p2d1f] (in the case of C4O4, at SCF level only). The computed energy release of the dissociation reaction (CnOn → n CO) of the two metastable structures is very high (about 100 kcal per mole of CO produced). It is of the same magnitude of the energy computed for the corresponding isoelectronic structures N4 and N8. If these or similar CO-clusters could be synthesized, these systems are candidates to be high energy-density materials (HEDM).
