Molecular Collision Diameters and Electronic Polarizabilities: Inherent Relationship and Fast Evaluation.

The collision diameter σ for a large set of molecular species is related to the static electronic polarizability αel. A remarkable correlation between these quantities conceptually similar to the analogous one previously identified for atoms is revealed. Our recommended model is the function σ(αel) = p1 + p2αel1/3, where p1 = 0.768 A and p2 = 2.168 are the fitting parameters providing the best overall match to the reference data for collision diameter (181 data points). The obtained correlation allows one to easily find the collision diameter of molecules from the known polarizability and vice versa. These findings can be useful for many applications, where there is a need for inexpensive assessments of the collision diameters or electronic polarizabilities, for example, when developing the transport property databases for modeling of chemically reacting flows.