The first set of 24 methods can be written as "DF-Dn/B". Here, "DF" denotes a correlation-exchange density functional, "Dn" is a dispersion correction, and "B" is the basis set used. For DF, we chose two pure generalized gradient approximation (GGA) functionals (BLYP and PBE ) and their popular hybrid counterparts (B3LYP, PBE0 ). As dispersion corrections (Dn), we considered D3(BJ) and the newly developed D4 corrections. As the basis sets (B), we used a small 6-31G basis set and two Karsruhe-type basis sets, def2-SVP and def2-TZVP. The second set of three methods includes three examples of 3c-composite methods, namely HF-3c, PBEh-3c, and r 2 SCAN-3c. The harmonic vibrational frequencies of the most abundant isotopologues after the geometry optimization at the corresponding level of theory were done using the ORCA 5 quantum-chemical software. With elements of the fifth row and beyond, the automatic effective core potentials def2-ECP for these elements were applied, as implemented in ORCA. For potentially conformationally flexible molecules, an initial conformational search was performed at the GFN2-xTB level of theory using the CREST software. Further optimization and harmonic frequency calculations were done for the lowest-energy conformer found.