Structure prediction of surface reconstructions by deep reinforcement learning
Søren Ager Meldgaard, Henrik Lund Mortensen, Mathias Jo̷rgensen, Bjørk Hammer
Abstract
Abstract We demonstrate how image recognition and reinforcement learning combined may be used to determine the atomistic structure of reconstructed crystalline surfaces. A deep neural network represents a reinforcement learning agent that obtains training rewards by interacting with an environment. The environment contains a quantum mechanical potential energy evaluator in the form of a density functional theory program. The agent handles the 3D atomistic structure as a series of stacked 2D images and outputs the next atom type to place and the atomic site to occupy. Agents are seen to require 1000–10 000 single point density functional theory evaluations, to learn by themselves how to build the optimal surface reconstructions of anatase TiO 2 (001)-(1 × 4) and rutile SnO 2 (110)-(4 × 1).