Fig. 1: Schematic illustration of the nature of the search space (discrete vs. continuous) in materials applications.
From: A Continuous Action Space Tree search for INverse desiGn (CASTING) framework for materials discovery
a depicts the typical potential energy landscape of materials with different metastable polymorphs at local minima. b depicts a discrete action space with defects movement as actions32. Moving from a high energy defect configuration situated at O to a relatively stable polymorph at A consists of finite movement in the defect configurational space where navigating the PES involves finite steps with a discrete jump in energy. c Crystal structure optimization represents a continuous action or search space problem with infinite possibilities of moving an atom giving a large number of pathways to navigate from high energy polymorph at O to local minima at A.
