Computer simulations of reactions, diffusion, and phase transitions are inevitable toward the molecular level understanding of various chemical processes, and in predicting material stabilities and properties. Often chemical reactions and transformations occur at time scales that are several orders of magnitude higher than that is accessible in molecular simulations. Moreover, many interesting systems are very large in size and it is impracticable to simulate them fully in silico. In my lecture, I will introduce some of the state of the art methods to tackle the time-scale and the length-scale bottlenecks, thus going beyond what was feasible a few years back using ab initio molecular dynamics. Three mutually different examples from my research lab will be briey presented: (a) mechanistic investigations of the Wacker process, (b) spontaneous evolution of H2 at hydroxylated rhodium/alumina interface, and (c) enzymatic reactions of lactamase.