Abstract
The structure and dynamics of liquids and glasses are usually discussed in terms of the short-range atomic structure and the nature of atomic bonds. However, many properties of liquids are rather similar and only weakly dependent on chemistry. Here we suggest that these properties are controlled not so much by the short-range atomic correlations but mainly by the medium-range density correlations which are similar among various liquids and supersede chemical details of the system. Taking metallic alloy liquids as examples we discuss the origin of the medium-range density correlations and argue they are only weakly dependent on the detailed nature of the atomic bond. By extrapolating the coherence of density correlation to infinity we can define an ideal glass state which is very diverse in the local atomic structure but is characterized by long-range density correlations.
Highlights
The atomic structure of liquid and glass appears random, but unlike gas they are condensed matters held together by cohesive force
The structure of liquid and glass is usually described by the atomic pair-distribution function (PDF), g (r) = 4π r2ρ0 N i,j δ r − ri − rj where ri is the position of the i-th atom at time t, ρ0 is the atomic density of N atoms, and denotes thermal average
The structure of liquid is described in terms of the same-time two body correlation function, the snapshot pairdistribution function (PDF)
Summary
The atomic structure of liquid and glass appears random, but unlike gas they are condensed matters held together by cohesive force. The structure of liquid and glass is usually described by the atomic pair-distribution function (PDF), g (r) = 4π r2ρ0 N i,j δ r − ri − rj where ri is the position of the i-th atom at time t, ρ0 is the atomic density of N atoms, and
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