Linearity condition for orbital energies in density functional theory (IV): Determination of range-determining parameter

This study explores the determination of the range-determining parameter in the orbital-specific (OS) range-separated hybrid functional by the linearity condition for orbital energies. The OS range-separated hybrid functionals with the optimized range-determining parameters exhibit a less fractional-occupation- number electron dependence for orbital energies and successfully estimate ionization potentials for valence as well as inner valence and core orbitals in the sense of Koopmans' theorem.