We report the results of a benchmarking study on generalized gradient approximation (GGA), meta-GGA, hybrid GGA, and hybrid meta-GGA density functional theory (DFT) methods for 3d transition metal mononitrides (3d-TMNs). The selected DFT functionals are, B97-D, BLYP, BP91, MPW91, PBE96, PW91, M06-L, B3LYP, B97, BHandH, PBE0, M05, M05-2X, M06, M06-2X, M06-HF and TPSSh. The performances of these DFT functionals are assessed by calculating the bond distance, harmonic vibrational frequency and atomization energy of 3d-TMNs. The results are compared with the available experimental and high-level ab initio results. The calculated results show that MPW91, M06-L, and B3LYP functionals provide better results than the other functionals that are taken in this study. In general, the functionals with significant Hartree-Fock exchange show poor performance in most of the 3d-TMNs. Hence, these functionals are not recommended for the studies of structure and energetics in 3d-TMNs. accuracy of multireference methods and less computation time. Generally, DFT methods act as an alternative to high cost ab initio methods. Because of very moderate overall O(N 2 ) scaling, they are computationally less expensive. From the literature, it can be noted that the DFT calculations were also performed on 3d Transition metal mononitrides (3d-TMNs). For instance, Daoudi et al. have performed both ab initio and DFT calculations on ScN. 24 They concluded that DFT methods are accurate but yield higher vibrational frequencies. Later, Chaudhari and Lee studied 3d-TMNs using B3LYP method and concluded that binding energies of 3d-metal mononitrides are higher than monocarbides and monoxides. 25 Even though plenty of experimental and theoretical studies on 3d-TMNs were reported in the literature, a satisfactory description of their electronic, structural, and elastic properties is still an area of active research.In the recent past, an enormous amount of exchange-correlation functionals developed within the DFT framework. Because of this, one needs to pay careful attention to the selection of functionals to study a particular atomic or molecular system. It is widely believed that B3LYP yields a better result in organic systems. In the case of inorganic systems, the selection of DFT functionals is a challenging one. Because metals possess near degenerate energy levels, subsequently these methods show difficulty in determining the ground state of a system. Hence, in order to find out suitable DFT functional, one needs to perform a benchmark study of DFT functionals on these systems. From the literature survey, it can be understood that no systematic DFT assessment study performed on 3d-TMNs, in particular, using recently developed DFT functionals and Minnesota functionals. Earlier, Wu has investigated the structure and energetic properties of 3d-TMNs using DFT methods. From this investigation, it was concluded that the calculated properties are highly dependent on the DFT functionals. 26 But, they selected very few DFT functionals for the study. Apart fr...
