Spin correlations of inhomogeneous valence bond solid chains

We consider a spacially inhomogeneous generalization of the valence bond solid (VBS) chain by permitting an arbitrary distribution of the numbers of valence bonds. We evaluate all two point correlation functions of these VBS states. The correlation functions turn out to factorize completely into a product of local factors. This leads to very simple rules for their evaluation and implies the breaking of correlations of higher rank by a single weak link.Research performed within the program of the Sonderforschungsbereich 341 supported by the Deutsche Forschungsgemeinschaft