MBAvol: An Interpretable Descriptor Scheme for Crystal-Density Modeling of HEDM

Here, we introduce the multibody approximation volume descriptor (MBAvol) for crystal-density (ρ_cryst) prediction. MBAvol represents molecular spatial information through physically motivated atomic and multibody volume terms derived from density functional theory and analytical fitting, thereby reducing the data required for accurate modeling.

The resulting regression model achieves a mean absolute error of 0.026 g/cm³ and performs well for energetic cocrystals. SHAP analysis of the MBAvol terms provides quantitative, chemically interpretable structure–density relationships, from which three design guidelines were derived. Guided by these relationships, eight candidate HEDMs with high predicted ρ_cryst were identified.