SCALING FACTORS FOR OBTAINING FUNDAMENTAL VIBRATIONAL FREQUENCIES AND ZERO-POINT ENERGIES FROM HF/6-31G-ASTERISK AND MP2/6-31G-ASTERISK HARMONIC FREQUENCIES

New scaling factors have been determined for obtaining fundamental vibrational frequencies and zero-point vibrational energies from harmonic frequencies calculated at the HF/6-31G* and MP2/6-31G* levels. The scaling factors: for the fundamental frequencies have been derived from a comparison of a total of 1066 calculated frequencies for 122 molecules with corresponding experimental values, while the zero-point energy scaling factors were determined from a comparison of the computed values with the experimental zero-point energies for a set of 24 molecules. The scaling factors recommended are, respectively, 0.8929 and 0.9427 for HF/6-31G* and MP2/6-31G* fundamental frequencies, and 0.9135 and 0.9646 for HF/6-31G* and MP2/6-31G* zero-point energies. RMS errors were determined to be around 50 cm(-1) for the HF and MP2 fundamental frequencies, and around 0.4 kJ mol(-1) for the HF and MP2 zero-point energies.