Crystal-GFN: sampling crystals with desirable properties and constraints

TL;DR

Crystal-GFN is a novel generative model that efficiently samples crystal structures with desirable properties and constraints, advancing the discovery of new materials for energy and environmental applications.

Contribution

It introduces a multi-environment GFlowNet approach for flexible, constraint-aware crystal structure generation, addressing key challenges in materials discovery.

Findings

Median formation energy of generated crystals is -3.2 eV/atom.

Successfully generates crystals with targeted band gaps.

Produces diverse, valid crystal structures with high property fidelity.

Abstract

The discovery of novel solid-state materials, such as electrocatalysts, super-ionic conductors, or photovoltaic materials, plays a critical role in addressing various global challenges. It has, for instance, the potential to significantly improve the efficiency of renewable energy production and storage, thereby making substantial contributions to climate crisis mitigation strategies. In this paper, we introduce Crystal-GFN, a generative model of crystal structures possessing desirable properties and constraints. Operating as a multi-environment, continuous-discrete GFlowNet, it sequentially samples structural attributes of crystalline materials, namely space group, composition and lattice parameters. This domain-inspired approach enables the flexible incorporation of physicochemical and geometric hard constraints. We demonstrate the capabilities of Crystal-GFN to efficiently discover diverse and valid crystals with various properties: low predicted formation energy (median -3.2 eV/atom), band gap close to a target value and high density. Overall, Crystal-GFN is a crystal generation method that addresses several existing challenges in the literature and opens promising paths for accelerating materials discovery with machine learning.