Polymers treated with the valence effective Hamiltonian

7 Polymers treated with the valence effective Hamiltonian 

Using the same type of LCAO expansion as for molecules (see eq. (2.8)), the crystal orbitals are expanded as Bloch sums of the basis function centred at site fi in cell /  

2N+/is the number of unit cells of the polymer chain. The LCAO expansion coefficient matrices C(k) and the corresponding energy eigenvalues, e(k), are obtained by solving the eigenvalue problem for each value of k- 

Similar to eq. (2.9), F and S are the effective Fock and overlap matrices, respectively. In this case the matrix elements are lattice sums over all unit cells in the crystal  

The one-electron valence effective Fock operator, /VEH is that introduced in section 2.5, eq. (2.15), but extended by summing over all unit cells in the polymer16  

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