A way of resolving the order-of-limit problem of Tao-Mo semilocal functional.

It is highlighted recently that the Tao-Mo (TM) [Phys. Rev. Lett. 117, 073001 (2016)] semilocal exchange-correlation energy functional suffers from the order-of-limit problem, which affects the functional performance for phase transition pressures [J. Chem. Phys. 152, 244112 (2020)]. The root of the order-of-limit problem of the TM functional inherent within the interpolation function, which switches between the compact density and the slowly varying density. In this paper, we propose a different switch function that avoids the order-of-limit problem and interpolates correctly between the compact density and the slowly varying fourth-order density correction. By circumventing the order-of-limit problem, the proposed form enhances the applicability of the original TM functional on the diverse nature of the solid-state properties. Our conclusion is ensured by examining the functional in predicting properties related to the general-purpose solids, quantum chemistry, and phase transition pressure. Besides, we reasonably discuss the connection between the order-of-limit problem, phase transition pressure, and band gap of solids.