Diffusing diffusivity model of a polymer moving on a spherical surface.

The movement of a polymer is modeled by Brownian motion accompanied with a fluctuating diffusion coefficient when the polymer is in contact with a chemostatted monomer bath triggering the chain polymerization, which is called a diffusing diffusivity (DD) model. In this paper, we extend the DD model from three dimensional Euclidean space to a two dimensional spherical surface. The DD model on the spherical surface is described by a coupling Langevin system in the directions of longitude and latitude, while the diffusion coefficient is characterized by the birth and death chain.