A perturbation treatment of the hartree-fock equations for the ground states of 3- to 10-electron atoms

The first-order hartree-fock (hf) equations for the ground state of atomic systems with 4 to 10 electrons are deduced from the corresponding unrestricted (uhf) equations given previously. The second-order hf energies are given exactly and the third-order energies very accurately. Each atom is treated as a special case of a general scheme. The third- order energy of lithium is calculated very accurately, completing linderberg's calculation. The hf ground state energies of atoms with 3-10 electrons are shown to differ very little from the corresponding uhf energies previously given. The zero- and first-order expectation values of various operators are related to their corresponding uhf values.