  Using the LDA+$\textit{U}_\text{sc}$ method, we present calculations phase
relations of iron monoxides involving five polytypes in multiple spin-state
configurations. The Hubbard parameter $U$ is determined self-consistently
simultaneously with the occupation matrix and structures at arbitrary
pressures. The Hubbard parameter strongly depends on pressure, structure, and
spin state. Comparison with experimental structural data indicates the
LDA+$\textit{U}_\text{sc}$ can predict structure, compression curves, phase
relations, and transition pressures very well for the insulating B1 and iB8
states. However, it requires additional calculations using the Mermin
functional that includes the electronic entropic contribution to the free
energy to obtain an nB8 metallic state and a consistent iB8 to nB8
insulator-to-metal transition pressure.
