Pariser-Parr-Pople model parametrizations

The term model Hamiltonian is more general. From this point of view the effective Hamiltonians and pseudo-Hamiltonians could also be considered as model Hamiltonians . However, for clarity, we suggest that the term model Hamiltonian should be used when some simplified form of an approximate Hamiltonian has been guessed from a preliminary physical analysis. In contrast with the effective Hamiltonians and the pseudo-Hamiltonians that can be obtained by means of well defined mathematical procedures, the model Hamiltonians are generally parametrized from experiment. They would involve the semi-empirical Hamiltonians of quantum chemistry and solid-state physics (Hiickel, Hubbard, Pariser-Parr-Pople (PPP),...). 

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