title: Anisotropy of stress correlation in two-dimensional liquids and a pseudospin model.
abstract: Liquids are condensed matter in which atoms are strongly correlated in position and momentum. The atomic pair density function (PDF) is used often in describing such correlation. However, elucidation of many properties requires higher degrees of correlation than the pair correlation. For instance, viscosity depends upon the stress correlations in space and time. In this paper, we examine the cross correlation between the stress correlation at the atomic level and the PDF for two-dimensional liquids. We introduce the concept of the stress-resolved pair distribution function (SRPDF) that uses the sign of atomic-level stress as a selection rule to include particles from density correlations. The connection between SRPDFs and stress correlation function is explained through an approximation in which the shear stress is replaced by a pseudospin. We further assess the possibility of interpreting the long-range stress correlation as a consequence of short-range Ising-like pseudospin interactions.
authors.affiliation: Department of Physics and Astronomy, Joint Institute of Neutron Science, University of Tennessee, Knoxville, Tennessee 37996, USA.
authors.forename: Bin
authors.initials: B
authors.lastname: Wu
authors.affiliation: Department of Materials Science and Engineering, University of Tennessee, Knoxville,Tennessee 37996, USA.
authors.forename: Takuya
authors.initials: T
authors.lastname: Iwashita
authors.affiliation: Department of Physics and Astronomy, Joint Institute of Neutron Science, University of Tennessee, Knoxville, Tennessee 37996, USA.|Department of Materials Science and Engineering, University of Tennessee, Knoxville,Tennessee 37996, USA.|Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Egami