Abstract
The adiabatic and diabatic potential energy curves and the spectroscopic constant of the CsNa molecule have been performed. We have used an ab initio approach based on non-empirical pseudopotentials for Cs(+) and Na(+) cores, parameterized l-dependent polarization potentials and full configuration interaction calculations. The diabatic potential energy curves have been calculated using the effective hamiltonian theory. Our spectroscopic constants for the ground and the first excited states are in good agreement with the available theoretical and experimental works.