Assessment of the SCAN Functional for Spin-State Energies in Spin-Crossover Systems

The strongly constrained and appropriately normed (SCAN) functional has been tested toward the calculation of spin-state energy differences in a data set of 20 spin-crossover (SCO) systems, ranging from d⁴ to d⁷. Results show that the SCAN functional is able to correctly predict the low-spin state as the ground state for all systems, and the energy window provided by the calculations falls in the approximate range of energies that will allow for SCO to occur. Moreover, the SCAN functional can be used in periodic boundary condition calculations, accounting for the effect of collective crystal vibrations and counterions in the thermochemistry of the spin transition. Our results validate this functional as a potential method for in silico screening of new SCO systems at both, molecular and crystal-packed levels.