Analysis of over-magnetization of elemental transition metal solids from the SCAN and three related density functionals.

Recent investigations have found that the strongly constrained and appropriately normed (SCAN) meta-generalized gradient approximation exchange-correlation functional significantly over-magnetizes elemental Fe, Co, and Ni solids [1]. The difficulty does not occur in SCAN-L (deorbitalized SCAN) [2]. The problem have been traced to the tendency to favor integer occupations, similar to a DFT+U treatment [3]. We discuss what properties of the SCAN, revSCAN and rSCAN functional forms are responsible for such errors, and why the SCAN-L functional does much better in this respect [2].

[1] Phys. Rev. Mater. 2, 063801 (2018); J. Chem. Phys. 149, 044120 (2018); Eur. Phys. J. B 91, 193 (2018); Phys. Rev. B 98, 094413 (2018); Phys. Rev. Lett. 121, 207201 (2018).
[2] Phys. Rev. B 100, 041113 (2019).
[3] Phys. Rev. B 100, 045126 (2019).