The generalized gradient approximation (GGA) proposed by Perdew, Burke, and Ernzerhof was chosen as the exchange-correlation functional. To address the known issue of overdelocalization associated with GGA functionals, the Hubbard U -correction was applied to the iron d-states, as suggested by Dudarev et al. Previous studies have indicated that the structural and electronic properties of Prussian white are best represented by applying distinct U -values to the two iron sites. Therefore, a Hubbard correction of 7 eV was assigned to the d-states of high-spin Fe 2+ , while a value of 3 eV was used for the d-states of low-spin Fe 2+ . To ensure convergence to the correct high-spin-low-spin spin state, the total excess majority spin electrons were held constant. The plane-wave cutoff was set to 550 eV, and a