  Atomistic simulations based on the first-principles of quantum mechanics are
reaching unprecedented length scales. This progress is due to the growth in
computational power allied with the development of new methodologies that allow
the treatment of electrons and nuclei as quantum particles. In the realm of
materials science, where the quest for desirable emergent properties relies
increasingly on soft weakly-bonded materials, such methods have become
indispensable. In this perspective, an overview of simulation methods that are
applicable for large system sizes and that can capture the quantum nature of
electrons and nuclei in the adiabatic approximation is given. In addition, the
remaining challenges are discussed, especially regarding the inclusion of
nuclear quantum effects (NQE) beyond a harmonic or perturbative treatment, the
impact of NQE on electronic properties of weakly-bonded systems, and how
different first-principles potential energy surfaces can change the impact of
NQE on the atomic structure and dynamics of weakly bonded systems.
