An ab initio study on the ground and low-lying doublet electronic states of linear C2As

Graphical abstract: Here we report the results of ab initio calculations of the geometry, adiabatic excitation energies and electric dipole moments of the low-lying doublet electronic states of linear C2As. We also discuss some peculiar details of the vibronic and spin-orbit structure in the X∼2Π and 12Δ states, being the subject of our previous paper. The results for transition moments between the vibronic energy levels within the ground electronic state are presented. Research highlights: → The present study represents a continuation of our theoretical work on spectroscopy of C2As. → We determine the equilibrium geometry and adiabatic transition energies of the low-lying doublet excited states. → We presented the vibronic transitions within the ground X∼2Π electronic state. - Abstract: The present study is closely related to a recently published paper on the X∼2Π-12Δ spectral system of C2As [S. Jerosimic, Lj. Stojanovic, M. Peric, J. Chem. Phys. 133 (2010) 024307]. Here we report the results of ab initio calculations of the geometry, adiabatic excitation energies and electric dipole moments of the low-lying doublet electronic states of linear C2As. We also discuss some peculiar details of the vibronic and spin-orbit structure in the X∼2Π and 12Δ states, being the subject of our previous paper. The results for transition moments between the vibronic energy levels within the ground electronic state are presented. The aim of the present study is to motivate new experimental studies on the title molecule and to facilitate the interpretation of the results of these investigations.