Quantification of geometric errors made simple: application to main-group molecular structures

Nearly all electronic structure simulations begin with obtaining approximate geometries, making a systematic quantification of errors in approximate molecular structures of key importance. Recently, the geometric energy offset (GEO) framework based on a single and natural measure for quantifying and analysing these errors has been proposed [J. Phys. Chem. Lett. 2020, 11, 99579964]. An accurate and way less costly approximation to GEO is utilized here to readily quantify errors in main-group structures and analyze them in a chemically intuitive way. The use of semiexperimental geometries as a reference further simplifies the analysis. The analysis reveals new insights into the geometric performance of methods, new rankings, as well as patterns across different classes of methods and basis sets that arise from the analysis.