  The nature of glassy dynamics and the glass transition are long-standing
problems under active debate. In the presence of a structural disorder widely
believed to be an essential characteristic of structural glass, identifying and
understanding key dynamical behaviors are very challenging. In this work, we
demonstrate that an energetic disorder, which usually results from a structural
disorder, is instead a more essential feature of glass. Specifically, we
develop a distinguishable-particle glassy crystal (DPGC) in which particles are
ordered in a face-centered cubic lattice and follow particle-dependent random
interactions, leading to an energetic disorder in the particle configuration
space. Molecular dynamics simulations in the presence of vacancy-induced
particle diffusion show typical glassy behaviors. A unique feature of this
molecular model is the knowledge of the complete set of inherent structures
with easily calculable free energies, implying a well-understood potential
energy landscape. Due to its simplicity, the study of the DPGC provides a
promising direction to unlock the mysteries of glass.
