Speaker
Description
In the framework of the perturbation theory we consider the fine structure of the energy levels of few-electron atoms and ions in the states with the dominant configuration containing one or two $p$-electrons (or one $d$-electron). Using highly accurate expansions
of the nonrelativistic wave functions in terms of all-particle explicitly correlated Gaussians, we derived analytical expressions for matrix elements and then evaluate
the expectation values of the spin-orbit and electron spin-spin interactions. We apply our approach to study the fine structure splittings in the ground $^3 P$ state of the carbon atom. The calculated fine structure includes the leading-order spin-orbit and electron spin-spin corrections ($\propto m\alpha^4)$, contribution from the electron anomalous magnetic moment ($\propto m\alpha^5$), and accounts for the coupling between the ground and low-lying excited states (off-diagonal matrix elements between $^3 P_0$ and $^1 S_0$ states, and between $^3 P_2$ and $^1 D_2$ states). The calculated values are compared with the available experimental data and NIST Atomic Spectra Database.
