Finding Useful Metastable Materials – New Perspectives on an Old Problem

Large-scale deployment of first-principles electronic structure calculations in combination with the ever-increasing power and availability of massively parallel supercomputers have launched in past couple of decades an entirely new paradigm in modern materials science. Intuition and serendipity that were the hallmarks of materials discovery are now complemented by theory-guided searches, which have resulted in a number of important findings. However, using theory and computations to propose, with a high degree of confidence, novel and useful metastable materials still represents a significant challenge. In this talk I will present our recent attempts to solving some of the problems hindering theory-guided discovery and design of metastable phases with the particular focus on covalent and partially ionic solids. More specifically, I will discuss experimental realizability (synthesizability) of metastable crystalline phases (or polymorphs) in connection to the specific features of the potential energy surface[1] leading to an effective computational methodology to search for, and rank potentially metastable states according to their realizability. Next, I will talk about our efforts in developing computational methods to enable large-scale assessment of the polymorph lifetimes [2,3]. These are predicated on the novel solution to the problem of finding an optimal atom-to-atom mapping between infinitely periodic systems. Lastly, an emerging description of disordered and glassy systems as statistical ensembles of ordered/crystalline local minima on the potential energy surface[4] will be discussed. This approach enables predictive modeling of atomic disorder and glasses without the need for experimental inputs. In all of these areas our recent developments offer predictions of relevant properties, which, in turn, allow for more rational and reliable searches for useful metastable materials. 
Refs:
[1] V. Stevanović, Phys. Rev. Lett. 116, 075503 (2016) 
[2] F. Therrien, P. Graf, and V. Stevanović, J. Chem. Phys. 152, 074106 (2020) 
[3] F. Therrien, and V. Stevanović, Phys. Rev. Lett. 125, 125502 (2020)
[4] E. B. Jones and V. Stevanović, npj Comput Mater 6, 56 (2020)