Theoretical study of the electronic states of Si2C
Résumé
The ground state and electronically excited singlet and triplet states of Si2C have been investigated by ab initio calculations. For the electronic ground state, rovibrational energy levels have been evaluated by a variational approach using several different potential energy functions. The equilibrium geometry, the centrifugal distortion constants, and the vibrational levels up to 1500 cm(-1) are given. The best function yielded an electronic barrier to linearity of 859 cm(-1). The changes in the K-a level structures of the rovibrational levels caused by this barrier are predicted to appear between the v(2) = 4 and v(2) = 6 vibrational states. The results are compared with available experiments and with those of other theoretical studies. The electronically excited singlet and triplet states have been characterized by their potential energy functions. The avoided crossings and conical intersections in the excited states have been located and their influence on the electronic spectra is discussed.