Hyperfine Contact Interactions in Oxygen Calculated by Many-Body Theory

Many-body perturbation theory, which has been used in previous atomic calculations, is applied to the calculation of the hyperfine contact interaction in the oxygen atom. Large cancellations have been found to occur between different types of diagrams. Both core polarization diagrams and also diagrams representing electron correlations have been found to contribute significantly. The final value for ${\left|\Psi \mathrm{}\right(0\left)\right|}^2$ is in good agreement with that measured by Harvey.