Crystal structure discovery and phase transition dynamics in coarse-grained models
Access to this document is restricted. Some items have been embargoed at the request of the author, but will be made publicly available after the "No Access Until" date.
During the embargo period, you may request access to the item by clicking the link to the restricted file(s) and completing the request form. If we have contact information for a Cornell author, we will contact the author and request permission to provide access. If we do not have contact information for a Cornell author, or the author denies or does not respond to our inquiry, we will not be able to provide access. For more information, review our policies for restricted content.
The design of materials with novel properties increasingly depends on controlling structure formation across length scales. In soft matter systems, self-assembly offers a powerful route to create ordered structures from the bottom up. Unlike atomic crystals, these materials are not constrained by fixed bonding rules and can explore a much broader configurational space. This flexibility could enable the emergence of highly complex and even previously unobserved crystal structures. However, the vastness of this design space makes it difficult to predict which structures will form and how they will evolve under given conditions, which remains a challenge in materials science. This thesis addresses that challenge through computational studies of particles interacting via minimal, tunable pair potentials. In the first part, a highly flexible interaction potential is developed to target the self-assembly of low-coordinated crystal structures. Systematic variation of the features of the interaction potential leads to the discovery of new crystal structures without atomic equivalents, spanning a wide range of local motifs. In the second part, spontaneous solid–solid phase transitions are investigated using pair potentials from the same family of minimal models. Using high-resolution and particle-resolved simulations, multiple kinetic pathways are revealed for the transformation between body-centered cubic (bcc) and face-centered cubic (fcc) crystals, including a two-step route via an intermediate body-centered tetragonal phase,a direct bcc-to-fcc transition, and a pathway mediated by local microstructural features. Finally, in the third part, a more complex transformation from the gamma-brass crystal structure to bcc is investigated, where the formation of correlated nanodomains is observed. These studies demonstrate how minimal models can elucidate both the kinetic and thermodynamic principles that govern structure formation in soft materials, advancing our ability to predict and control materials behavior through particle–particle interaction design.