  Even though the viscosity is one of the most fundamental properties of
liquids, the connection with the atomic structure of the liquid has proven
elusive. By combining inelastic neutron scattering with the electrostatic
levitation technique the time-dependent pair-distribution function (i.e. the
Van Hove function) has been determined for liquid Zr80Pt20. We show that the
decay-time of the first peak of the Van Hove function is directly related to
the Maxwell relaxation time of the liquid, which is proportional to the shear
viscosity. This result demonstrates that the local dynamics for increasing or
decreasing the coordination number of local clusters by one determines the
viscosity at high temperature, supporting earlier predictions from molecular
dynamics simulations.
