Ab initio study of the structure and vibrational frequencies of the 2B2 state of AlC2H4

Abstract

The structure and harmonic frequencies of the ²B₂ state of AlC₂H₄ have been determined at the SCF level using a triple-ζ plus polarization (TZ2P) basis set. A binding energy of the complex of 9–10 kcal mol^–1 has been determined with electron correlation calculated using configuration interaction including all single and double excitations (CISD). The vibrational frequencies have been predicted using the scaled quantum-mechanical force field method and yields values in better agreement with experiment than those from a CISD calculation. A more weakly bound complex at a longer Al⋯C₂H₄ distance is found, but may be a computational artefact.