  The macroscopic behaviors of materials are determined by interactions that
occur at multiple lengths and time scales. Depending on the application,
describing, predicting, and understanding these behaviors require models that
rely on insights from electronic and atomic scales. In such cases, classical
simplified approximations at those scales are insufficient, and quantum-based
modeling is required. In this paper, we study how quantum effects can modify
the mechanical properties of systems relevant to materials engineering. We base
our study on a high-fidelity modeling framework that combines two
computationally efficient models rooted in quantum first principles: Density
Functional Tight Binding (DFTB) and many-body dispersion (MBD). The MBD model
is applied to accurately describe non-covalent van der Waals interactions.
Through various benchmark applications, we demonstrate the capabilities of this
framework and the limitations of simplified modeling. We provide an open-source
repository containing all codes, datasets, and examples presented in this work.
This repository serves as a practical toolkit that we hope will support the
development of future research in effective large-scale and multiscale modeling
with quantum-mechanical fidelity.
