Spectroscopic constants and molecular properties of [formula omitted], A2Π u, [formula omitted] and D2Π g electronic states of the [formula omitted] ion

Abstract

The potential energy curves (PECs) of X 2 Σ g + , A 2 Π u , B 2 Σ u + and D 2 Π g electronic states of N 2 + ion have been studied using the full valence complete active space self-consistent-field (CASSCF) method followed by the highly accurate valence internally contracted multireference configuration interaction (MRCI) approach together with the aug-cc-pCV5Z basis set within the frozen core approximation for internuclear separations from 0.05 to 1.8 nm. And the spectroscopic parameters ( T e , R e , ω e , ω ex e , B e , α e , D 0 and D e ) of three isotopologues ( 14 N 2 + , 14N 15N + and 15 N 2 + ) have been determined. These parameters have been compared in detail with those of previous study reported in the literature, and excellent agreement has been found between the present results and the experimental data. With these PECs, the complete vibrational states for the 14 N 2 + , 14N 15N + and 15 N 2 + isotopologues are computed for the four electronic states. For each electronic state of each non-rotating isotopologue, the vibrational level G υ , inertial rotation constant B υ and centrifugal distortion constant D υ have been reported for the first 30 vibrational states, which agree well with the available experimental data. The ro-vibrational levels have been predicted when the rotational quantum number J is lower than 40 ( J ≤ 39) for these electronic states of 14 N 2 + species for future experimental or theoretical research.