title: Elementary excitations and crossover phenomenon in liquids.
abstract: The elementary excitations of vibration in solids are phonons. But in liquids phonons are extremely short lived and marginalized. In this Letter through classical and ab initio molecular dynamics simulations of the liquid state of various metallic systems we show that different excitations, the local configurational excitations in the atomic connectivity network, are the elementary excitations in high temperature metallic liquids. We also demonstrate that the competition between the configurational excitations and phonons determines the so-called crossover phenomenon in liquids. These discoveries open the way to the explanation of various complex phenomena in liquids, such as fragility and the rapid increase in viscosity toward the glass transition, in terms of these excitations.
authors.affiliation: Department of Physics and Astronomy, Joint Institute for Neutron Sciences, University of Tennessee, Knoxville, Tennessee 37996, USA.
authors.forename: T
authors.initials: T
authors.lastname: Iwashita
authors.affiliation: Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: D M
authors.initials: DM
authors.lastname: Nicholson
authors.affiliation: Department of Physics and Astronomy, Joint Institute for Neutron Sciences, University of Tennessee, Knoxville, Tennessee 37996, USA and Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA and Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA.
authors.forename: T
authors.initials: T
authors.lastname: Egami