Fig. 1
From: Construction of ground-state preserving sparse lattice models for predictive materials simulations
Schematic of the two types of ground-state inconsistencies that may arise during the fit of a cluster expansion (CE) model to DFT reference data. (P1) illustrates the situation in which one particular configuration, s1, that is unstable based on the DFT input data becomes a stable ground-state of the CE model, as its CE energy is below the convex combination of its decomposition line defined by the ground-state configurations h2 and h3. (P2) illustrates the converse situation in which the CE energy of one ground-state configuration, h2, is greater than the convex combination of the neighboring ground states, h1 and h3, which causes h2 to be unstable in the CE model
