Remarks on phase choices for the electronic wavefunctions when carrying out vibronic or rovibronic energy level and intensity calculations for molecules exhibiting a Jahn-Teller effect

Hamiltonian matrix and two sets of eigenvectors representing fixed-nuclei Born-Oppenheimer electronic wavefunctions. Wavefunctions on the left are complex and transform into themselves when the vibrational coordinate ϕ is taken once around the conical intersection at Q = 0. Wavefunctions on the right are real and transform into their negatives when the vibrational coordinate ϕ is taken once around the conical intersection at Q = 0.