  The correct treatment of d electrons is of prime importance in order to
predict the electronic properties of the prototype chalcopyrite semiconductors.
The effect of d states is linked with the anion displacement parameter u, which
in turn influences the bandgap of these systems. Semilocal exchange-correlation
functionals which yield good structural properties of semiconductors and
insulators often fail to predict reasonable u because of the underestimation of
the bandgaps arising from the strong interplay between d electrons. In the
present study, we show that the meta-generalized gradient approximation
(meta-GGA) obtained from the cuspless hydrogen density (MGGAC) [Phys. Rev. B
100, 155140 (2019)] performs in an improved manner in apprehending the key
features of the electronic properties of chalcopyrites, and its bandgaps are
comparative to that obtained using state-of-art hybrid methods. Moreover, the
present assessment also shows the importance of the Pauli kinetic energy
enhancement factor, $\alpha=(\tau-\tau^W)/\tau^{unif}$ in describing the d
electrons in chalcopyrites. The present study strongly suggests that the MGGAC
functional within semilocal approximations can be a better and preferred choice
to study the chalcopyrites and other solid-state systems due to its superior
performance and significantly low computational cost.
