Reproduce and quantify the GMTKN55 accuracy gap of the low-cost r2SCAN-D4 functional (WTMAD-2)

GMTKN55 is a benchmark of 1505 relative energies across 55 subsets (thermochemistry, kinetics/barrier heights, noncovalent and intramolecular interactions) with high-level reference values (mostly CCSD(T)/CBS or better). Method quality is summarized by the weighted total mean absolute deviation WTMAD-2 (in kcal/mol). Using an open quantum-chemistry code (Psi4, PySCF, or ORCA) and a large basis set (def2-QZVP or aug-def2-QZVP), compute the full-GMTKN55 WTMAD-2 for the dispersion-corrected meta-GGA r2SCAN-D4 and reproduce the published value of $\approx 7.5$ kcal/mol to within $\pm 0.5$ kcal/mol. Then quantify the accuracy gap to the double-hybrid frontier ($\text{WTMAD-2} \approx 2.5$ kcal/mol): which of the 55 subsets contribute most to r2SCAN-D4's error, and by how much does adding a dispersion correction (D4 vs no dispersion) change WTMAD-2? r2SCAN-D4 is a rung-3, non-hybrid functional cheap enough to run the whole database on a workstation.

Acceptance. FULLY RESOLVES: a full-GMTKN55 evaluation of r2SCAN-D4 (all 55 subsets, all 1505 reference reactions) with an open QM code and a stated basis set, giving overall WTMAD-2 within $\pm 0.5$ kcal/mol of 7.5, plus the per-subset MAD breakdown identifying the top error-contributing subsets and the WTMAD-2 shift from removing the D4 correction, all with a runnable script and the raw single-point energies. PARTIAL: a reproducible evaluation over a clearly named representative subset (e.g. the 'GMTKN30' or 'diet-GMTKN55' reduced set) with its WTMAD-2, or a documented convergence/basis-set issue preventing agreement. Metric: WTMAD-2 in kcal/mol computed with the standard scheme-2 weights; report the exact basis and integration-grid settings so the number is comparable.