Potential parameters and eigen spectra of improved Scarf II potential energy function for diatomic molecules

Abstract

In this paper, Scarf II potential is used to construct the improved Scarf II potential energy function (ISPEF) for applications to diatomic molecules. Conditions to be satisfied by a diatomic molecule potential are applied in the derivation of potential parameters of the ISPEF. Equation of bound state ro-vibrational energies is obtained for the ISPEF via a Pekeris-type approximation to the centrifugal term of the Schrödinger equation. The ISPEF and expression for eigen energies are used to model spectroscopic data of five diatomic molecules: N2+(X1∑g+), Na2 (c1 Πu), ScI (B1 Π), NaK (c3 Σ+) and CO (X1 Σ+). Average absolute deviation from dissociation energy (AAD) and mean absolute percentage deviation from Rydberg-Klein-Rees data (MAPD) are used to analyse data. On the basis of AAD as goodness-of-fit index, the ISPEF represents a near-perfect model for the diatomic molecules analysed and also a better model than the existing literature data of improved Tietz potential for the Na2 (c1 Πu) molecule. On the other hand, with the MAPD as goodness-of-fit index, the available literature results show that eigen energies of ISPEF are equivalent to ro-vibrational energies of Morse and improved generalised Pöschl-Teller potentials in fitting spectroscopic data of CO (X1 Σ+) molecule.