  Inelastic neutron scattering measurements are presented which show the abrupt
development of new oxygen lattice vibrations near the doping-induced
metal-insulator transition in La(2-x)Sr(x)CuO(4). A direct correlation is
established between these lattice modes and the electronic susceptibility (as
measured by photoemission) inferring that such modes mix strongly with charge
fluctuations. This electron-lattice coupling can be characterized as a
localized one-dimensional response of the lattice to short-ranged metallic
charge fluctuations.
