SEARCH Articles Figures Tables 6, orbital perturbation matrix element Coupled-perturbed Hartree-Fock orbital theory First-order spin-orbit perturbation Introduction perturbational molecular orbital Mixing of Degenerate Orbitals— First-Order Perturbations Mixing of Non-Degenerate Orbitals— Second-Order Perturbations Molecular orbital method and sum-over-states perturbation theory Molecular orbital methods perturbation theory Orbital interaction perturbation Orbital perturbation theory Orbital perturbed Orbital perturbed Orbitals and Geometrical Perturbation Orbitals of Diatomic Molecules and Electronegativity Perturbation Orbitals perturbations Orbitals perturbations Perturbation Theory—Orbital Mixing Rules Perturbation configuration interaction using localized orbitals Perturbation degenerate orbitals Perturbation method three-orbital systems Perturbation molecular orbital method Perturbation molecular orbital theory Perturbation of the molecular orbitals Perturbation spin-orbit Perturbation theory applied to spin-orbit coupling Perturbation theory correcting bond orbitals Perturbation theory crystal orbital structures Perturbation theory orbital corrections Perturbation theory orbital interaction Perturbational Approaches to Spin-Orbit Coupling Perturbational Molecular Orbital (PMO) Approach Perturbational Molecular Orbital (PMO) Method Perturbational Molecular Orbital Theory (PMO) Applied to Oxetane Formation Perturbational molecular orbital Perturbational molecular orbital approach Perturbational molecular orbital calculations Perturbational molecular orbital method Perturbational molecular orbital theory Perturbative Configuration Interaction using Localized Orbitals Perturbative Configuration Interaction with Localized Orbitals Qualitative Model Perturbation Molecular Orbital Theory Quantum chemistry perturbation molecular orbital theory Spin-orbit coupling perturbation theory Spin-orbit coupling perturbative handling Spin-orbit interaction perturbation Spin-orbit interaction perturbation theory Spin-orbit perturbation matrix elements Spin-orbit perturbed wave functions Spin-orbital perturbed Three-orbital perturbation