Equilibrium Structures of Propane and 2,2-Difluoropropane and Comparison with Other Two-Top Molecules.

The Born-Oppenheimer ab initio equilibrium structures of propane (CH)CH and 2,2-difluoropropane (CH)CF were computed at the CCSD(T) level of theory using a basis set of quadruple zeta quality. The semiexperimental structure of propane was also determined from the ground state rotational constants corrected for rovibrational corrections calculated at the MP2 level of theory. Structural comparisons are made with other molecules and are discussed in terms of the quantum theory of atoms in molecules.