Critical evaluation of semi-empirical methods for calculating molecular diffusion coefficients

Abstract Various methods for determining molecular diffusion coefficients have been evaluated and compared for a range of different chemical compounds. It was shown that electrochemical methods have a larger error compared to non-electrochemical methods. A critical analysis of the molecular volumes obtained by quantum chemical modeling at the semi-empirical level showed that the PM6-D3 method was the most accurate for calculating the diffusion coefficients. The results obtained using the PM6-D3 Hamiltonian correlated with experimental data and the results of calculations using the ABC method (R = 0.99). Among the six equations relating the diffusion coefficient to molecular volume, the Hayduk-Laudie equation was found to have an error of less than 8%, which is comparable to the error in determining this parameter experimentally. Thus, this model allows accurate theoretical predictions of diffusion coefficients for inorganic ions, macromolecules, and carbon nanomaterials, provided that the structure of the molecule/nanoparticle is sufficiently rigid.