How Global is the Global Instability Index?

The global instability index (GII) is an inexpensive bond valence theory-based metric originally designed to evaluate the total bond strain in a crystal. Although prior studies have proven GII is an effective predictor of structural distortions and decomposition energy when applied to small data sets, the wider use of GII as a global indicator of structural stability has yet to be evaluated. To that end, we compute GII for thousands of compounds in inorganic structure databases and partition compounds by chemical interactions underlying their stability to understand GII. We find that structural prototype, chemistry, and electronic character significantly impact the GII of a crystal, contraindicating its use as a general measure of the feasibility of a structure.