Accurate variational calculations of the ground ²P ^o(1s ²2s ²2p) and excited ²S(1s ²2s2p ²) and ²P ^o(1s ²2s ²3p) states of singly ionized carbon atom

In this article we report accurate nonrelativistic variational calculations of the ground and two excited states of C ⁺ ion. We employ extended and well optimized basis sets of all-electron explicitly correlated Gaussians to represent the wave functions of the states. The optimization of the basis functions is performed with a procedure employing the analytic gradient of the energy with respect to the nonlinear parameters of the Gaussians. The calculations explicitly include the effects due to the finite nuclear mass. The calculated transition energies between the three states are compared to the experimentally derived values. Finally, we present expectation values of some small positive and negative powers of the interparticle distances and contact densities.