Polarizability calculations on water , hydrogen , oxygen , and carbon dioxide

Based on the semiclassical model of damped oscillators, a procedure is developed for the calculation of the dispersion of refractive index, polarizability, and dielectric permeability, which are treated as complex quantities. Using experimental values of refractive indices and employing the frequencies of strong absorption bands, a least squares fit is used to determine oscillator strengths and damping factors. The absorption coefficient and the imaginary part of the refractive index are also calculated at the corresponding wavelengths. The procedure is applied for the cases of water, hydrogen, and oxygen in both the liquid and gaseous states and for gaseous carbon dioxide, and a good agreement is obtained between calculated and observed values of refractive indices. Results are also compared with those of previous calculations. Calculated absorption coefficients agree well with experimental values in the region of absorption bands. The calculated values of oscillator strengths and damping factors are discussed. The previously determined values for the polarizability extrapolated to infinite wavelength agree with the present results for the contribution of the electronic motion to the polarizability, this contribution being about the same for both the liquid and gaseous states of hydrogen, oxygen, and water. The value obtained in the present work for the polarizability of liquid water is about 2.8-fold greater than the results of previous calculations; most of the contribution is due to atomic and molecular motions. Onsager's theory is shown to yield the experimental value of the permanent dipole of water from the dielectric constant of liquid water when our result for the polarizability of liquid water is employed.