Structures and harmonic frequencies of sulfur-containing molecules: Assessment of the 1/4 exchange-correlation functional†
The performance of the 1/4 generalised gradient approximation (GGA) exchange-correlation functional is assessed for the calculation of Kohn–Sham optimised geometries and harmonic vibrational frequencies of a benchmark of sulfur-containing molecules. Overall, the 1/4 results are a notable improvement over those of HCTH-93, which has previously been shown to be to a significant improvement over BLYP. The 1/4 quality is comparable to that of MP2 and the hybrid functional B3P86. The results provide further evidence that 1/4 is a useful functional for structural and harmonic frequency calculations, particularly given that it does not contain any fraction of exact orbital exchange.