Accurate variational calculations of energies of the 22S, 22P, and 32Dstates and the dipole, quadrupole, and dipole-quadrupole polarizabilities and hyperpolarizability of the lithium atom

The combined configuration-interaction–Hylleraas method has been used to calculate the energies for the ground 2 ${}_{}{}^2{}_{}{}^{}$S and the excited 2${\mathrm{}}^2$P and 3 ${}_{}{}^2{}_{}{}^{}$D states of the lithium atom. The energies obtained, -7.478 060 1 a.u. for the 2 ${}_{}{}^2{}_{}{}^{}$S state, -7.410 155 4 a.u. and -7.335 523 1 a.u. for the 2 ${}_{}{}^2{}_{}{}^{}$P and 3 ${}_{}{}^2{}_{}{}^{}$D states, respectively, are the lowest nonrelativistic variational upper bounds found so far. Ionization potentials, lifetimes, dipole oscillator strengths and their sums, dynamic dipole, quadrupole and dipole-quadrupole polarizabilities, and the static second hyperpolarizability are also reported and compared with experimental and other theoretical results.