H ₂ X100: A Gold-Standard CCSD(T)/CBS Benchmark Dataset of Binding Energies, Structures, and Harmonic Frequencies for (H ₂ X) <i> _n </i> , X = S, Se, Te, <i>n</i> = 2–4, and Assessment of Lower-Scaling Density Functio

We constructed a benchmark dataset (H2X100) of 100 CCSD(T)/Complete Basis Set (CBS) binding energies for the (H2X)n, X = S, Se, Te, n = 2–4 clusters, and additional CCSD(T)-quality structures and harmonic vibrational frequencies for 12 unique homodimer minima, containing a mix of the hydrogen and chalcogen bonding motifs. Using the new H2X100 dataset, we assessed the performance of 17 density functionals across the rungs of Jacob’s ladder, with and without dispersion corrections, spanning the GGA, mGGA, GH-GGA, GH-mGGA, RSH-GGA, and RSH-mGGA groupings. The r2SCAN-D4, B97M-rV, and ωB97M-V functionals provide the best agreement with the CCSD(T) benchmarks and can be used in studies of larger ensembles of these systems, including simulations of their condensed phases.