Computational Discovery at the Interface of Chemistry and Materials: 1D Carbon Nanothreads and 2D Polar Metals

The total number of equilibrium crystal structures composed from subsets of the periodic table is likely bounded fairly strictly by phase separation of multi-component mixtures. In contrast, the design space afforded by metastable structures is essentially unbounded: the key challenge here is to craft kinetic constraints that access structures with compelling properties. One strategy to this end deploys the immense design power of synthetic organic chemistry within a solid-state context to produce carbon nanothreads of diverse compositions and properties as ordered lattices comprising uniquely one-dimensional sp³ or mixed sp²/sp³ macromolecules at the ultimate juncture between crystalline rigidity and molecular control. These systems exhibit unique behaviors as the thinnest possible objects whose rigidity is maintained by covalent bonds. In two dimensions, kinetic control in service of unique structure can also be obtained by crafting similarly unique synthesis "containers", for example the gallery between silicon carbide and epitaxial graphene, which can host a broad family of epitaxial, air-stable, crystalline two-dimensional polar metals with record-breaking optical nonlinearities, excellent surface-enhanced Raman performance, and intriguing prospects for the integration of metals into quantum heterostructures. In both cases, predictive computational theory can provide strong guiding principles.