A CASSCF-CI study of the ground and low-lying excited electronic states of C2H+2

✍ Scribed by Wolfgang P. Kraemer; Wolfram Koch

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 578 KB
• Volume: 212
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(93)85496-b

✦ Synopsis

Complete-active-space SCF and multi-reference configuration interaction calculations employing large Gaussian basis sets of the general contraction type have been carried out to determine the equilibrium structures and relative stabilities of the ground electronic state R 'I& of the acetylene cation C,H; and its low-lying excited electronic states, the A 'Zp' and B 'C: states, as well as their HCC-H dissociation behavior. While the % and B states have linear equilibrium structures, the first excited A state has a trans-bent equilibrium geometry with a bond angle of approximately 112". The C-H bond dissociation energy of the ion and parent neutral ground states were obtained in good agreement with experimental findings, whereas the first ionization potentials of C2H, and C,H derived from the differences between the energies of the ion and the parent neutral were found to be too small by about 0.2 eV. The present results were used to set a theoretical lower limit of 17.30 eV for the appearance energy of the CzH+ radical ion by dissociative photoionization of C2HZ and lo discuss possible reaction pathways for this process.