  A recently published analytical model, describing and predicting elasticity,
viscosity, and fragility of metallic melts, is applied for the analysis of
about 30 nonmetallic glassy systems, ranging from oxide network glasses to
alcohols, low-molecular-weight liquids, polymers, plastic crystals, and even
ionic glass formers. The model is based on the power-law exponent lambda
representing the steepness parameter of the repulsive part of the inter-atomic
or -molecular potential and the thermal-expansion parameter alpha_T determined
by the attractive anharmonic part of the effective interaction. It allows
fitting the typical super-Arrhenius temperature variation of the viscosity or
dielectric relaxation time for various classes of glass-forming matter, over
many decades. We discuss the relation of the model parameters found for all
these different glass-forming systems to the fragility parameter m and detect a
correlation of lambda and m for the non-metallic glass formers, in accord with
the model predictions. Within the framework of this model, thus the fragility
of glass formers can be traced back to microscopic model parameters
characterizing the intermolecular interactions.
