By averaging over atomic details,
coarse-grained (CG)
models provide
profound computational and conceptual advantages for studying soft
materials. In particular, bottom-up approaches develop CG models based
upon information obtained from atomically detailed models. At least
in principle, a bottom-up model can reproduce all the properties of
an atomically detailed model that are observable at the resolution
of the CG model. Historically, bottom-up approaches have accurately
modeled the structure of liquids, polymers, and other amorphous soft
materials, but have provided lower structural fidelity for more complex
biomolecular systems. Moreover, they have also been plagued by unpredictable
transferability and a poor description of thermodynamic properties.
Fortunately, recent studies have reported dramatic advances in addressing
these prior limitations. This Perspective reviews this remarkable
progress, while focusing on its foundation in the basic theory of
coarse-graining. In particular, we describe recent insights and advances
for treating the CG mapping, for modeling many-body interactions,
for addressing the state-point dependence of effective potentials,
and even for reproducing atomic observables that are beyond the resolution
of the CG model. We also outline outstanding challenges and promising
directions in the field. We anticipate that the synthesis of rigorous
theory and modern computational tools will result in practical bottom-up
methods that not only are accurate and transferable but also provide
predictive insight for complex systems.