Electronic Structure and Thermodynamic Properties of LaC₂

Ab initio self-consistent field (SCF), Møller−Plesset second-order perturbation theory (MP2), complete active space multiconfiguration self-consistent field (CASSCF) followed by multireference singles and doubles configuration interaction (MRSDCI), and relativistic configuration interaction (RCI) studies to include the spin−orbit effects were carried out on LaC 2 . The enthalpy of the La(g) + 2C(graph) = LaC 2 (g) reaction as well as the atomization and dissociation (La−C 2 ) energies were computed for the theoretically determined structure. The experimental Gibbs energy functions (GEF) were corrected by using the symmetrical C 2 v structure instead of the assumed (incorrect) unsymmetrical linear geometry. The corrected experimental enthalpies thus obtained agree with the theoretically computed results.