Grain diffusion and chemical evolution in protoplanetary disks

In this contribution, we treat the diffusion and vertical sedimentation of dust particles in a turbulent protoplanetary accretion disk. Based on the derivation of the diffusion coefficient, we calculate the vertical distribution of the grains. Furthermore, we develop a model which couples the disk dynamics with the chemical evolution of the gas-phase species. To begin with, we consider the time-dependent chemistry in a 1+1 D accretion disk model. The calculations demonstrate that vertical abundance gradients develop. We then include vertical diffusion processes. This is an important step towards a realistic modeling of multidimensional chemical processes in protoplanetary disks.