Calculation of oscillator strengths using the density matrix renormalisation group method

We present a scheme for the calculation of oscillator strengths between the salient molecular states in correlated models of conjugated polymers using the density matrix renormalisation group method. The accuracy of the method is demonstrated by comparison with exact solutions. The method is applied to a model of polyacetylene in order to identify the dominant transitions, and hence the key states participating in non-linear optical properties.