Symmetry—adapted method fragmentation

To construct the MO of the H2O molecule, we shall allow the atomic orbitals of the central oxygen atom to interact with the symmetry-adapted orbitals on the hydrogen atoms (the fragment method). We have already established the symmetry properties of the various orbitals Civ point group), and they are repeated in Figure 6.4. It is easy to check visually that the orbitals with the same symmetry on two different fragments have a non-zero overlap, whereas those with different symmetries have zero overlap ( by symmetry ). 

Flick, J. C., Kosenkov, D., Hohenstein, E. G Sherrill, C. D., and Slipchenko, L. V. (2012]. Accurate prediction of noncovalent interaction energies with the effective fragment potential method Comparison of energy components to symmetry-adapted perturbation theory for the S22 test set,/. Chem. Theory Comput 8, pp. 2835-2843, doi 10.1021/ct200673a. 

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