On correlation effects in diffusion of nonspherical particles in amorphous solids

Abstract

The possibility of correlated diffusion jumps of nonspherical molecules in amorphous solids is discussed. The main reason of the correlated jumps are the nonspherical terms in the molecular interaction potential. These terms lead to nonisotropic particle escape from an arbitrary cell of the matrix in which the diffusion occurs. If also the molecular orientation in the cell is remembered, this results in correlated directions of diffusion jumps. The peculiarities of correlated jumps are considered in a correlation matrix approach. In particular, it is shown that the jump correlation leads to a disturbance of the classical linear dependence of ln D on T −1. In calculating the correlation multiplier the point symmetry of diffusing molecules is recognized. The correlation order is shown to depend on the symmetry of the molecular field. The correlated jumps of diatomic or linear molecules accelerate the diffusion transfer.