In computational mechanics focusing on engineering applications, the integration of simulation techniques which consider the atomistic or molecular structure of matter is still a challenge. This is particularly true for amorphous materials like polymers: There, the molecules are typically chain-like and can form, dependent on the class of polymers, e.g., entanglements and/or crosslinks. This requires simulation techniques that are capable of these peculiarities and can handle them appropriately across the scales. Strategies which have been established for crystalline materials are usually not sufficient. This contribution focuses on the Capriccio method as a multiscale domain-decomposition strategy that employs the fine-scale, discrete atomistic or molecular description only in regions of a specimen exposed to high loads or exhibiting, e.g., material or geometric discontinuities. These regions are embedded in a continuum as a field-based approach. The purpose of the continuous domain is typically two-fold: Firstly, it reduces the computational cost in regions which do not require the fine-scale resolution. Secondly, it provides non-periodic boundary conditions to the atomistic or molecular domains, which, in classical molecular dynamics applications, are typically considered under periodic boundary conditions. Some examples from recent research activities highlight the capabilities of the Capriccio method: Obtaining continuum mechanical constitutive descriptions in the vicinity of nano-scaled filler particles of polymer composites and studies of fracture in polymers and other amorphous materials.