Static and dynamic polarisabilities, Cauchy coefficients and their anisotropies: a comparison of standard methods

The static and dynamic polarisabilities of a range of small molecules have been calculated and compared with earlier experimental and computational work. The polarisabilities have been calculated using SCF and density functional theory (DFT) methods, the latter using local and non-local, hybrid functionals. Calculations at several low frequencies enable the Cauchy moment S(−4) to be found for both the isotropic and anisotropic polarisabilities. Results have been computed using two basis sets, Sadlejʹs medium-size polarized basis set and Dunningʹs correlation consistent triple-zeta basis set augmented with additional polarisation functions. The DFT values obtained with the hybrid functional are in good agreement with both experimental values and coupled-cluster results.