Ab-initio Calculation of Electronic, Vibrational,Rotational and Thermochemical Properties of C₂ and C₃ Ground States

Using HF/6-31g basis set to optimize the equilibrium geometrics, the results for \mathrmC_2\left(X^+ \Sigma_\mathrmz^+\right) has been found to be Re = 1.2623 A, and for \mathrmC_3\left(\tildeX^1 \Sigma_\mathrmR^+\right) to be linear with R_e = 1.2833Å. The discussion on the results proposes that it is necessary to take the electron-vibration interaction and the anharmonicity in the ground electronic state of C₃ into account in order to obtain the more exact data for C₃. The electronic,vibrational, rotational and thermochemical properties of \mathrmC_2\left(X^+ \Sigma_\mathrmz^+\right) and \mathrmC_3\left(\tildeX^1 \Sigma_\mathrmR^+\right) and have been given in detail.