Accurate ab initio ro-vibronic spectroscopy of the X²∏ CCN radical using explicitly correlated methods

Hill, J.G., Mitrushchenkov, A., Yousaf, K.E. and Peterson, K.A. (2011) Accurate ab initio ro-vibronic spectroscopy of the X²∏ CCN radical using explicitly correlated methods. Journal of Chemical Physics, 135(14), p. 144309. (doi: 10.1063/1.3647311)

Abstract

Explicitly correlated CCSD(T)-F12b calculations have been carried out with systematic sequences of correlation consistent basis sets to determine accurate near-equilibrium potential energy surfaces for the X²∏ and a⁴Σ⁻ electronic states of the CCN radical. After including contributions due to core correlation, scalar relativity, and higher order electron correlation effects, the latter utilizing large-scale multireference configuration interaction calculations, the resulting surfaces were employed in variational calculations of the ro-vibronic spectra. These calculations also included the use of accurate spin-orbit and dipole moment matrix elements. The resulting ro-vibronic transition energies, including the Renner-Teller sub-bands involving the bending mode, agree with the available experimental data to within 3 cm⁻¹ in all cases. Full sets of spectroscopic constants are reported using the usual second-order perturbation theory expressions. Integrated absorption intensities are given for a number of selected vibronic band origins. A computational procedure similar to that used in the determination of the potential energy functions was also utilized to predict the formation enthalpy of CCN, ΔH_f(0K) = 161.7 ± 0.5 kcal/mol.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Hill, Dr John
• Authors: Hill, J.G., Mitrushchenkov, A., Yousaf, K.E., and Peterson, K.A.
• College/School: College of Science and Engineering > School of Chemistry
• Journal Name: Journal of Chemical Physics
• ISSN: 0021-9606
• ISSN (Online): 1089-7690
• Copyright Holders: Copyright © 2011 American Institute of Physics
• First Published: First published in Journal of Chemical Physics 135(14):144309
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher