Analysis of the Effect of Translation−Rotation Coupling on Diffusion along the Molecular Axes

The analysis of the microscopic diffusion processes of CO(2) and H(2)O in the coordinate system defined by the molecular orientation allows a new criterion to be introduced which provides information on the short and long time behavior of the rotation-translation coupling as well as to quantify the strength of this coupling. We discuss the general conditions under which this affects the translation diffusion "seen" by the molecule along its molecular axes. The results show that the translation-rotation coupling is correlated to the local environment in shaping the longitudinal and transversal translation dynamics of a molecule at a microscopic level.