Correlated-Gaussian calculations of the ground and low-lying excited states of the boron atom

Benchmark variational calculations of the four lowest P-2 and S-2 states of the boron atom (including the ground state) have been performed. The wave functions of the states have been expanded in terms of all-particle explicitly correlated Gaussian basis functions and the finite mass of the nucleus has been explicitly accounted for. Variational upper bounds for the nonrelativistic finite-and infinite-nuclear-mass energies of all considered states have been obtained with the relative convergence of the order of 10(-7)-10(-8). Expectation values of the powers of the inter-particle distances and Dirac delta functions depending on those distances have also been computed. These calculations provide reference values that can be used to test other high-level quantum chemistry methods.