| The microscopic structure of fluid systems at equilibrium is related with the state they locate.The radial distribution function,RDF,can be used to characterize the microscopic structures of both simple and complex fluids.Through RDF,it is easy to know the phase the fluid system locates,but it is difficult to fix its state at equilibrium.When the interaction potential is well known,the phase diagram of the fluid system can be assured.In the diagram of the Lennard-Jones fluids,the state at equilibrium can be described by(ρ*,β*).The pressure can be calculated by the corresponding equation of state.Here,ρ*=ρσ3 is the reduced density,β*=(?)/kBT is the reduced temperature,ρ is the density,σ is the distance between two bodies when the Lennard-Jones potential energy is zero,(?) is the depth of the Lennard-Jones potential well,kB is the Boltzmann constant and T is the temperature at equilibrium.It is meaningful to explore and build a connection between the microscopic structure of the fluid system at equilibrium and its state(ρ*,β*).In this thesis,molecular dynamical simulations are used to simulate a series of Lennard-Jones fluid systems at equilibrium,and the connection between the microscopic structure of the fluid system at equilibrium and its state(ρ*,β*)is studies.We found that there is a one to one map between the first peak(rpeak*,gpeak)of the RDF of the fluid system at equilibrium and it state(ρ*,β*),and empirically built two correlations for them.Through our correlations,it is convenient for researchers to obtain(ρ*,β*)through(rpeak*,gpeak).At the same time,it is also convenient for researchers to obtain(rpeak*,gpeak)through(ρ*,β*).This work is scientifically meaningful for us to better understand the properties of the Lennard-Jones fluids,and can be extended to fluid systems with other potentials such as the Yukawa potential. |
