The Chemical Bond Formation Energy Based on Rigid Atomic Orbitals

8 The Chemical Bond Formation Energy Based on Rigid Atomic Orbitals 

The above discussion of the potential energy should be unsettling we have found that it is the kinetic energy in H2 that stabilizes the chemical bond with the electron in the ground state, while the potential energy is destabilizing. This seems to contradict the commonly proposed picture of the chemical bond, in which the overlap density stabilizes the 

We will find that the potential energy is important and stabilizing the bond. The fault lies in the use of the AOs to construct MOs. We have treated these as rigid entities with a radial decay set for the atomic state, but this is not appropriate to the molecular environment. 

To show how the rigid orbital model fails, we will estimate the bond formation energy using the terms described above and test the validity of the result with the virial theorem. Using the experimental H2 bond length of 2 bohr from Table 7.1, we find 

For Equation (A 10.29), working through the integrals with Mathematica gives 

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