Three-body exchange energies in H-3 and He-3 calculated by the surface integral method

Repulsive three-body exchange energies are calculated for H-3 and He-3 usin g a new method based on an extension of the surface integral method to thre e-body interactions. The dependence of the three-body exchange energies on the internuclear distances between 5 and 10 a(0) is investigated for equila teral configurations. The angular dependence is also studied for geometries in which two distances are fixed at equal distances. Very good agreement w ith other calculations at the same level of approximation is obtained for H -3 as well as for He-3. The relative importance of the different electron p ermutations in He-3 is discussed. (C) 2000 American Institute of Physics. [ S0021-9606(00)30118-0].