Theoretical characterization of the ground state of the alkaline-earth monocarbides: Ordering of the two lower-lying states of the BeC, MgC, and CaC molecules

✍ Scribed by Clarissa O. Da Silva; Fábio Eduardo C. Teixeira; José André T. Azevedo; Edilson C. Da Silva; Marco Antonio Chaer Nascimento

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 425 KB
• Volume: 60
• Category: Article
• ISSN: 0020-7608
• DOI: 10.1002/(sici)1097-461x(1996)60:1<433::aid-qua42>3.0.co;2-a

✦ Synopsis

The two lower-lying electronic states (32and '2-1 of the BeC, MgC, and CaC molecules were investigated using restricted Hartree-Fock (RHF), generalized valence bond (GVB), and configuration interaction (CI) calculations to establish the relative ordering of those states as a function of the size of the alkaline-earth element. It is shown that as a result of the competition between bonding effects, which predominate for the 2states, and exchange effects, which stabilize the 52states, the ordering of these states can be reversed as we move from the Be to the Ca atom. For both the BeC and MgC molecules, the ground state was found to be a triplet X 3 2state, but for the CaC molecule, the high-spin X 5 Cbecomes more stable. 3 0 1996 John Wiley & Sons, Inc.

characterization and identification of these molecules is based mostly on spectroscopic measurements, the determination of their ground states and the calculation of their spectroscopic constants he identification of the Sic [l] molecule in became an important theoretical problem.

T space [l] has prompted the search for other Besides the astrophysical interest, the theoreti- monocarbide molecules. Since the experimental cal investigation of the ground state of these