Shifted 1/N expansion for the energy levels of the Varshni potential

Abstract

The shifted large-N method is applied to the eigenvalue problem of Varshni's third potential, which provides a good representation of the potential energy curves of many covalent diatomic molecules. Analytical results for the vibrational and rovibrational energy levels of I2(X), CO(X) and H2(X) molecules compare fairly well with the exact ones obtained numerically. The accuracy of the eigenvalues is found to depend significantly on the width of the potential.