Interatomic exchange energies

Interatomic Exchange Energies in Some Simple Molecules. 102... 

Table 3 Interatomic exchange energies of some simple molecules at HF/6-311G(d,p)//HF/6-311G(d,p) level... 

Fig. 8 The interatomic exchange energies found in N-methylacetamide as a function of intemuclear distance...

This relationship, known as Bloch s rule, applies in the localized-electron limit where the interatomic spin-spin interaction is described by the superexchange perturbation theory of eq. (23) with 7n J J is the Heisenberg exchange energy. Calculations by Shrivastava and... 

In contrast with the EHF energy, which can generally be estimated by ab initio methods for many systems of practical interest (see ref. 140 for a semiempirical treatment), the interatomic correlation energy is most conveniently approximated from the dispersion energy by accounting semiempiri-cally for orbital overlap and electron exchange effects. Thus the following... 

The second bond b d) in vhich the interatomic distance is 2 8 A contributes nothing to the energy of the molecule. The exchange energy of the bond a—c is compensated by repulsion energy of the non-bonding electrons of a and and c and d (— 2 X a/Q). The energy of structure // is thus less than /, but the superposition of the tw o structures leads to an additional stabilization of the system. 

---