Theoretical molecular structure and experimental dipole moment of cis-1-chloro-2-fluoroethylene

The equilibrium geometry of cis-1-chloro-2-Ñuoroethylene has been evaluated using two di†erent ab initio methods : the coupled-cluster (CC) approach and MÔllerÈPlesset perturbation theory. Accurate predictions have been obtained. Using both methods, the dipole moment has been estimated numerically as energy derivative with respect to an applied electric Ðeld at zero Ðeld strength. The experimental dipole moment of cis-1-chloro-2-Ñuoroethylene has been determined by observing the Stark spectrum of the J \ 40, 4 ^ 31, 3 and J \ 41, 3 ^ 40, 4 transitions. The spectrum proÐle has been Ðtted to a model function computed as a sum of Lorentzian proÐles over the hyperÐne-Stark components, whose frequencies have been derived by diagonalizing the full rotationalÈquadrupole-Stark Hamiltonian matrix for each value of the applied electric Ðeld. Very good agreement between experimental and theoretical dipole moment has been obtained.