# Is it possible to evaluate rotational and vibrational partition functions for diffusion in the Eyring Theory of Absolute Rates?

Let us consider the usual expression for Diffusion processes and diffusion coefficients in the Eyring's theory:

$$D=\lambda^2k = \lambda^2 \frac{k_BT}{h}\frac{\Omega_\ddagger}{\Omega}e^{-\frac{\epsilon_0}{k_BT}}$$

I would like to use this formulation to relate molecular partition functions, molecular structure, and $$D$$. To do so for aqueous solutions, I need to take in account, while evaluating rotational and vibrational partition functions, that internal motion is closely related to hydrogen bonding.

I think that the main contribution to the alteration of degrees of freedom for a molecule in diffusion processes is the translational one, but taking in account that, it is likely that the movement of a molecule determines an alteration in the intermolecular interactions (which in water are not negligible). For that reason, I would like to know if there is a way to take that into account while evaluating the partition functions.