Relativistic spinless energies and thermodynamic properties of sodium dimer molecule

Relativistic spinless rotational-vibrational energy eigenvalue relation has been obtained by solving the Klein-Gordon equation in the presence of General Molecular potential (GMP). The relativistic energy eigenvalue relation has been reduced to the non-relativistic one in the non-relativistic limit. Relativistic and non-relativistic vibrational energies have been computed for the 51Δg state of Na2 molecule and compared with Rydberg-Klein-Rees (RKR) data. It has been concluded that depending on relation between scalar and vector potentials, relativistic effect can cause a slight decrease in the vibrational energies or can lead to an increase. In addition, thermodynamic properties such as vibrational mean energy U, vibrational specific heat C, vibrational free energy F and vibrational entropy S for Na2(51Δg) molecule have been examined with respect to temperature and the values of principal quantum number.