Role of linear velocity in ‘‘rotational’’ diffusion

Abstract

By considering afresh the three-dimensional diffusion of an asymmetric top molecule, new statistical cross-correlation functions are reported using computer simulation. Off-diagonal elements exist directly in the laboratory frame (x,y,z) of the tensor cross-correlation function between a molecule’s Coriolis acceleration, 2ω×v at time t and its own angular velocity ω at t=0. Here v is the molecule’s center-of-mass linear velocity. This is the first clear evidence that the historically popular theory of rotational diffusion is in need of development at a fundamental level to involve directly the linear velocity v.