Thomas–Fermi–Dirac interaction potentials for rare gas systems

The energy components and the Thomas–Fermi–Dirac interatomic interaction potentials of the Ar–Ar, Kr–Kr, and Xe–Xe systems are calculated for several internuclear distances, solving exactly the Thomas–Fermi–Dirac equation for the diatomic systems. Comparisons are made to results from other density functional approaches. The dependence of the energy components on the nuclear charge is discussed, and it is suggested that (EαTFD −EαTF)/EαTF, the relative deviation of a TFD energy component from that calculated from the Thomas–Fermi density, is proportional to Z−2/3. A possible analytic form of the interatomic potential is proposed.