Investigations on spectroscopic properties of ND(X3Σ−) radical using coupled‐cluster theory in combination with the correlation‐consistent quintuple basis set augmented with diffuse functions

Abstract

AbstractThe coupled‐cluster singles‐doubles‐approximate‐triples [CCSD(T)] theory in combination with the correlation‐consistent quintuple basis set augmented with diffuse functions (aug‐cc‐pV5Z) is used to investigate the spectroscopic properties of the ND(X3Σ−) radical. The adiabatic potential energy curve is calculated over the internuclear separation range from 0.06 to 2.47 nm and fitted to the analytic Murrell–Sorbie function, which is used to determine the spectroscopic parameters, ωeχe, αe, and Be. The present De, Re, ωe, ωeχe, αe, and Be values are of 3.57357 eV, 0.10367 nm, 2403.166 cm−1, 42.888 cm−1, 0.25344 cm−1, and 8.90867 cm−1, respectively, which are in excellent agreement with the available measurements. With the potential obtained at the UCCSD(T)/aug‐cc‐pV5Z level of theory, a total of 21 vibrational states is predicted when J = 0 by numerically solving the radial Schrödinger equation of nuclear motion. The complete vibrational levels, classical turning points, inertial rotation, and centrifugal distortion constants are reproduced for the ND(X3Σ−) radical when J = 0 for the first time, which are in good accord with the available RKR data. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009