Electron correlation in diatomic molecules

Abstract

This thesis investigates the use of some new techniques in obtaining approximate solutions to Schrodingers equation for diatomic molecules. The aim of this work was to develop some general methods that could be applied to any small diatomic molecule and would allow calculation of expectation values to a greater degree of accuracy than traditional methods. Throughout this work we assume the wavefunction of a diatomic molecule may be written in the form [Diagram] where the ψI's are the antisymmetric product of single electron spin orbitals i.e. [Diagram] The ϕi's are described in the confocal elliptical coordinates λ,μ and ϕ. This coordinate system is the 'natural' one to choose for diatomic molecules. The one electron H⁺₂ molecular ion may be rigourously factored into products of the form [Diagram] and products of this form are a convenient representation of molecular orbitals for larger molecules. For the work described in this thesis it was essential to describe the molecular spin orbitals as a product of functions of a single variable multiplied by a spin function. The form described in (1.3) was used.