An exchange-based diagnostic for static correlation

We propose here a DFT-based diagnostic for static correlation %TAEX[TPSS@HF - HF] which effectively measures how different the DFT and HF exchange energies given density are. This %TAEcorr[TPSS] are two cost-effective priori estimates adequacy of importance correlation. contains nearly same information as earlier A diagnostic, but may be more intuitive to understand. Principal component variable clustering analysis large number diagnostics reveals much variation is explained by just components, almost all it four; these blocked four clusters (single excitations; entropy; double pragmatic energetics).