Improved Thomas-Fermi interaction potential for atoms with very dissimilar nuclear charges

Abstract

The interaction potential, U(R), for atoms with nuclear charges Z a and Z 2 (Za >>Z2) is discussed. It is shown that within the linear approximation in Z2/Z 1 this potential is determined by the atomic screening function, q~(R; Z), alone. On the basis of the Thomas-Fermi model allowing for quantum corrections, several universal expressions for ~o(R; Z) are suggested. They permit reliable estimates of U(R) up to R,-~2 a.u. and for Z2/Z 1 ~, 1/5.