Therefore, energy calculations and geometry optimizations at the CASPT2/PCM level should be performed exclusively for γ = ϕ . Note that γ and ϕ are determined by the character of the state rather than its energetic order, which may differ at the SCF and PT2 levels. Consequently, the RFROOT and RLXROOT keywords must be specified separately in the input file to define ϕ and γ, respectively.