The vibrational frequencies of difluoroethyne

Abstract

Ab initio coupled-cluster calculations with single and double excitations (CCSD) and with a perturbational treatment of connected triple excitations [CCSD(T)] are reported for difluoroethyne using large basis sets. The results for the trans-bending mode ν4 are extremely sensitive to electron correlation and basis set effects. The best theoretical and experimental estimates for the fundamental vibrational frequencies are in excellent agreement.