Sammendrag
Sammendrag: Processes at interstellar ice surfaces form a challenging field of study, well suited for methods of computational chemistry. To date the number of such computational studies remains rather limited. Computer simulations are a valuable complement to experiments on astrochemically relevant systems. An overview will be given of suitable computational tools to study thermal and UV induced processes. Some examples will be given from simulations on the photodesorption of water ice and the hydrogenation of CO ice.