Theoretical Studies On The Accurate Analytical Potential Energies Of Diatomic Molecules And Molecular Ions XY～+

There are two parts in this dissertation. In part one, the potential energies of some electronic states of several diatomic halogen molecules are studied using the energy consistent method (ECM). In part two, an ECM for ions (ECMI) is proposed and applied to study the potential energies of the electronic states of diatomic molecular ions XY? based on the physical picture of the ECM and variational principle.In the first section, different methods used to study potential energies of neutral diatomic molecules are analyzed. The ECM method is applied to study the potential energies of halogen diatomic molecules. The results show that the ECM potential behaves well in whole internuclear region, and that the ECM not only gives satisfied potentials for smaller diatomic molecules but also generates correct potential energies for heavier molecules like halogen diatomic molecules. In the second section, an energy consistent method for ion (ECMI) and an ECMI potential function are proposed to study the potential energies of diatomic molecular ions XY?. Since the Coulomb potential included in the ECMI potential of molecular ion is well chosen and variationlly determined, the ECMI potential is superior to other analytical potential energies of diatomic molecular ions. The ECMI potential is used to study the potential energies of some electronic states of some diatomic molecular ions XY?. The results show that the new ECMI potential not only behaves excellently in the ionic equilibrium region but also gives correct potential energy data in ionic asymptotic and dissociation area where experimental approaches and ab initio methods such as CI(configuration interaction) may have difficulty to obtain reliable potential data.