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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
Author(s) -
Da Silva Clarissa O.,
Teixeira Fábio Eduardo C.,
Azevedo José André T.,
Da Silva Edilson C.,
Nascimento Marco Antonio Chaer
Publication year - 1996
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/(sici)1097-461x(1996)60:1<433::aid-qua42>3.0.co;2-a
Subject(s) - chemistry , molecule , valence (chemistry) , alkaline earth metal , ground state , atomic physics , spin states , atom (system on chip) , physics , alkali metal , inorganic chemistry , computer science , embedded system , organic chemistry
The two lower‐lying electronic states ( 3 Σ − and 5 Σ − ) 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 3 Σ − states, and exchange effects, which stabilize the 5 Σ − states, 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 Σ − state, but for the CaC molecule, the high‐spin X 5 Σ − becomes more stable. © 1996 John Wiley & Sons, Inc.