if (sapt_dft_functional != "HF") and ((mon_a_shift == 0.0) or (mon_b_shift == 0.0)):
        raise ValidationError('SAPT(DFT): must set both "SAPT_DFT_GRAC_SHIFT_A" and "B".')

    if (core.get_option('SCF', 'REFERENCE') != 'RHF'):
        raise ValidationError('SAPT(DFT) currently only supports restricted references.')