Semiempirical Hamiltonians, effective operators

The Hiickel method is an approximation scheme for finding the coefficients in the delocalized LCAOMOs. It is called a semiempirical method, because various quantities are not calculated explicitly, but are assigned values to agree with experiment. We sume that the Hamiltonian is a sum of effective one-electron Hamiltonian operators, Heff. in which all attractions and repulsions are expressed in some approximate way, so that the wave function will be a product of orbitals and each orbital can be treated separately. We apply the variation method, minimizing the orbital energy W obtained from the wave function

[Pg.887]

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