DFT Calculation Details. The seven exchange-correlation functionals employed in the present study are described in Table . Grimme's D3 dispersion correction with Becke-Johnson damping parameters [D3(BJ)] was applied to all functionals. The chosen functionals encompass a range of theoretical approximations, from pure GGA to double-hybrid GGA. As the trends observed in the present study often coincide with the unofficial rungs of Jacob's ladder proposed by Perdew, we include them for ease of classification in the later discussion. All structures were optimized using the def2-TZVP basis set using each of the first six functionals in Table . After optimization, single point calculations were performed using the def2-QZVPP basis set. Stability analysis was performed on the wavefunctions, and where necessary, the calculations were restarted using rotated orbitals until stability was achieved.