Rovibrational Energies of Triatomic Molecules by Means of the Rayleigh–Schrödinger Perturbation Theory

A theoretical study of FeNC in the 6Δ electronic ground state

“…From the resulting ab initio data, we have obtained values of the standard spectroscopic parameters of FeN 12 C and FeN 13 C (Table 3). Further, we have determined analytical representations of the potential energy functions and have solved the corresponding rotation-vibration Schrö dinger equation by means of the MORBID program [31][32][33][34] and by means of an adiabatic-separation method [36]. FeNC has been investigated experimentally by Lie and Dagdigian [1] in a laser-fluorescence-excitation experiment, and our theoretical calculations reproduce very satisfactorily the observed value of the m 3 fundamental energy of FeN 12 C together with the observed values of the effective rotational constants B 0,X=9/2 for the X = 9/2 spin-orbit components of the FeN 12 C and FeN 13 C vibronic ground states [1].…”

“…[36]). In the case of FeNC, the non-adiabatic couplings are rather small and can initially be neglected.…”

“…As explained in [36], a parameterized function of (r N-C ; R Fe-G , s) has been fitted through the ab initio points for FeNC, and the optimized parameter values were used as input for the adiabatic calculation, in which we neglect the non-adiabatic couplings mentioned in the preceding paragraph. In Table 8, we present for FeN 12 C the resulting vibrational energy spacings and averaged geometrical parameters.…”