BASIS SET SUPERPOSITION ERROR EFFECTS ON NU-FX, NU-FX...N STRETCHING MODES OF HYDROGEN-BONDED SYSTEMS FX...NCH (X = H, D)

Basis set superposition error (BSSE) effects on combination vibrational frequencies are presented for the rapid nu(F-H) and slow nu(FX...N) stretching modes of FX...NCH (X = H, D) hydrogen-bonded complexes at the SCF and MP2 levels. Calculations reported here have been made with a large basis set on the FX...NCH complexes at the SCF and MP2 levels. The BSSE effect is calculated using the counterpoise method. The nu(FX) and nu(FX...N) stretching modes are calculated by means of the variational method, taking into account the mechanical anharmonicity and anharmonic coupling between these vibrations. It is shown that combination transitions are located on both sides of the main nu(FX) transition almost at the same place with both SCF and MP2 BSSE corrected results and that their intensities are similar.