Vibrational frequencies for the classical and nonclassical forms of protonated acetylene–C2H+3

The equilibrium geometries and harmonic vibrational frequencies of the classical and nonclassical structures of H3C+2 have been predicted using ab initio molecular electronic structure theory. Self-consistent-field (SCF) methods were used with a double zeta plus polarization (DZ+P) basis set. For the complete set of normal modes of vibration for both structures, the infrared intensities have been predicted. In addition, for a subset of these harmonic frequencies, actual vibrational fundamentals have been estimated using scaling techniques.