This paper presents calculations of the third-order susceptibility in the alkali metal vapors involving spin-orbit coupling in the energy spectrum of the alkali atoms and some power transfer between the atoms in the ensemble and their surroundings, including the radiation field. The results are plotted as a function of wavelength in the vicinity of the neodymium and iodine laser lines, and their second, third, and fourth harmonics for each of the alkalies; i.e., 10 520 Å < (

) < 10 720 Å, and 13 070 Å < (

) < 13 230 Å, respectively.