Electron- and hole-hopping amplitudes in a diatomic molecule. II. Effect of radial correlations

Phys.Rev. B48, 3340 (1993)

We continue our study of electron- and hole-hopping amplitudes in diatomic molecules. Here, we go beyond the Hartree approximation and use two different orbital exponents for the two-electron atom. It is found that the difference in hopping amplitudes between electrons and holes ( Delta t) is enhanced when the effect of radial correlations is taken into account. A tight-binding model with two orbitals per site is used to represent the results of the first principles calculation and gain insight into the physical origin of the quantity Delta t.