Isotropic and anisotropic interaction induced scattering in liquid argon (original) (raw)
Related papers
Effects of dispersion forces on the structure and thermodynamics of fluid krypton
Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics, 2000
Semianalytical and numerical calculations are performed to predict the structural and thermodynamic properties of low-density Kr fluid. Assuming that the interatomic forces can be modelled by a pairwise potential plus the three-body Axilrod-Teller potential, two different routes are explored. The first one is based on the hybridized mean spherical approximation integral equation of the theory of liquids and the second one uses large-scale molecular dynamics (MD). Algorithms for MD simulation are constructed on parallel machines to reduce the amount of computer time induced by the calculations of the three-body forces and the pair-correlation function. Our results obtained with the two methods mentioned above are in quite good agreement with the recent small-angle neutron-scattering experiments [Formisano et al., Phys. Rev. Lett. 79, 221 (1997); Benmore et al., J. Phys.: Condens. Matter 11, 3091 (1999)]. Moreover, the reliability of the asymptotic form of the integral equation is ass...
Effects of three-body interactions on the structure and thermodynamics of liquid krypton
The Journal of Chemical Physics, 2002
Large-scale molecular dynamics simulations are performed to predict the structural and thermodynamic properties of liquid krypton using a potential energy function based on the two-body potential of Aziz and Slaman plus the triple-dipole Axilrod-Teller (AT) potential. By varying the strength of the AT potential we study the influence of three-body contribution beyond the triple-dipole dispersion. It is seen that the AT potential gives an overall good description of liquid Kr, though other contributions such as higher order three-body dispersion and exchange terms cannot be ignored.
Molecular Physics, 2003
The internal energies and compressibility factors of argon, krypton and xenon have been simulated using recent state-of-the-art ab initio pair intermolecular potentials and the best semi-empirical pair potentials, and the Axilrod-Teller-Muto three-body term. The results are compared with experimental data for both sub-critical and super-critical temperatures and for densities ranging up to a 2.5 multiple of the critical density. Both the ab initio and semi-empirical results for argon are in very good agreement with the experimental ones. For krypton and xenon, the ab initio results are worse than the semi-empirical results but they are still acceptable.
International Journal of Heat and Mass Transfer, 2009
In this work we calculate the transport properties of liquid argon flowing through a nanochannel formed by krypton walls. Non-equilibrium molecular dynamics (NEMD) simulations are performed assuming flow conditions corresponding to the macroscopic equivalent of planar Poiseuille flow. We examine the effect of channel width and system temperature on diffusion coefficient, shear viscosity and thermal conductivity. The results show clearly the existence of a critical width, in the range 7–18σ, below which the behavior of transport properties is affected in comparison to bulk properties. In fact for small width values, diffusion coefficient is highly anisotropic, the component normal to the wall being the smaller one. For the same width range, diffusivities along all directions are higher in the central layers than those close to the walls. Similarly, shear viscosity increases for small channel width values while thermal conductivity decreases. All properties approach bulk values as the channel width increases. The layers close to the walls always present distinctly different behavior due to the interaction with the wall atoms. The observed behavior is of particular importance in the design of nanofluidic devices.
Coherent-and Incoherent-Scattering Laws of Liquid Argon
Physical Review A, 1972
The inelastic-scattering functions for liquid argon have been measured at 85. 2 K. The coherent-scattering function was obtained from a measurement on pure A36 and the incoherentscattering function was derived from the result obtained from the A36 sample and the result obtained from a mixture of A3 and A for which the scattering is predominantly incoherent. The data, which are presented as smooth scattering functions at constant values of the wavevector transfer in the range l.0-4.4 A, are corrected for multiple-scattering contributions and for resolution effects. Such corrections are shown to be essential in the derivation of reliable scattering functions from neutron-scattering data. The incoherent-scattering function is compared to recent molecular-dynamics results and the mean-square displacement as a function of time is derived. The coherent-scattering function is compared to molecular-dynamics results and also, briefly, to some recent theoretical models.
Interaction-induced absorption in argon-krypton mixture clusters: Molecular-dynamics study
Physical Review A, 1998
Molecular-dynamics ͑MD͒ simulations have been used to calculate the many-body time-correlation functions and interaction-induced absorption spectra for the small clusters composed of binary argon ͑Ar͒-krypton ͑Kr͒ mixtures. The liquid state phase of Ar k Kr 13Ϫk (0ϽkϽ13) clusters has been studied, and considerable differences between the interaction-induced absorption of the clusters and bulk matter are observed.
The Journal of Chemical Physics, 2019
We have implemented a scheme for classical molecular dynamics simulations of collision-induced absorption. The program has been applied to a gas mixture of argon (Ar) and krypton (Kr). The simulations are compared with accurate quantum dynamical calculations. The comparisons of the absorption coefficients show that classical molecular dynamics is correct within 10% for photon wave numbers up to 220 cm−1 at a temperature of 200 K for this system. At higher temperatures, the agreement is even better. Molecular dynamics accounts for many-body interactions, which, for example, give rise to continuous dimer formation and destruction in the gas. In this way, the method has an advantage compared with bimolecular classical (trajectory) treatments. The calculations are carried out with a new empirical Ar–Kr pair potential. This has been obtained through extensive analysis of experimental thermophysical and transport properties. We also present a new high level ab initio Ar–Kr potential curve...
Many-body interaction effects on the low-k structure of liquid Kr
Physical review. E, Statistical, nonlinear, and soft matter physics, 2001
Neutron diffraction measurements and theoretical calculations of the structure factor S(k) of liquid Kr are extended to small k values (k<4 nm(-1)). The results show that many-body interaction contributions have an increasing effect on S(k) as k-->0, reaching at least 40% of the measured intensity. Both the phase diagram and the low-k structural data of dense Kr turn out to be closely reproduced by the hierarchical reference theory if additional many-body forces are taken into account by an augmented strength of the Axilrod-Teller triple-dipole potential. The experimental density derivative of S(k) is also used for a very sensitive test of the theories and interaction models considered here.
Specific properties of argon-like liquids near their s pinodals
Journal of Molecular Liquids, 2017
The work is devoted to the computer simulation study of the spinodal position for argon and low-molecular liquids having the averaged interparticle potentials similar to that for argon. For this purpose several new methods are developed: the study of the intersection points for pressure curves on pairs of two close isochors, specific changes for the isochoric behavior of the radial correlation functions near the spinodal, non-trivial changes of the temperature dependencies for isochoric values of the self-diffusion coefficient, kinematic shear viscosity and Maxwell relaxation time of argon at the intersection of its spinodal. The three last characteristics are determined with the help of analysis of long time tails for the velocity auto-correlation function. Obtained in such a way the position of spinodal is compared with that following from the experimental study and computer simulations of the isothermal compressibility.