Variational calculations on the 2P1/2 ground state of boron atom using hydrogenlike orbitals

Variational calculations of the 2P1/2 ground state of boron atom are performed using a single-term reference wave function and a 150-term wave function expansion without interelectronic distances. The wave function is constructed with hydrogenlike orbitals. These orbitals are superior to Slater orbitals, because the orbital 2s contains nodes. The calculated energy -24.550233 a.u. is compared with -24.541246 a.u. using Slater orbitals and the same basis function expansion, and with -24.5689998 a.u. obtained from full-CI calculations using a 4-31G basis set. The single-term wave function constructed with hydrogenlike orbitals leads to an energy value of-24.501187 a.u., which is lower than the Hartree-Fock energy using a single-zeta basis set of Slater orbitals and it is also lower than with a single-term wave function with Slater orbitals, both lead to an energy of-24.498369 a.u. The behavior of the node of the 2s orbital and its radial distribution function of the wave function series are discussed.