Editing Argon

'''Argon''' (Ar) has long been a popular choice for [[Computer simulation techniques |computer simulations]] of simple liquids. Some of the first computer simulations of liquid argon were those of Wood and Parker in 1957 <ref>[http://dx.doi.org/10.1063/1.1743822 W. W. Wood and F. R. Parker "Monte Carlo Equation of State of Molecules Interacting with the Lennard‐Jones Potential. I. A Supercritical Isotherm at about Twice the Critical Temperature", Journal of Chemical Physics '''27''' pp. 720- (1957)]</ref>  and of Rahman in 1964 <ref name="Rahman" >[http://dx.doi.org/10.1103/PhysRev.136.A405 A. Rahman "Correlations in the Motion of Atoms in Liquid Argon", Physical Review '''136''' pp. A405–A411 (1964)]</ref>. Sadus and Prausnitz have shown that three-body repulsion makes a significant contribution to [[Idealised models#Three-body potentials|three-body interactions]] in the liquid phase
<ref>[http://dx.doi.org/10.1063/1.471172 Richard J. Sadus and J. M. Prausnitz "Three-body interactions in fluids from molecular simulation: Vapor–liquid phase coexistence of argon", Journal of Chemical Physics '''104''' pp. 4784-4787 (1996)]</ref>
(for use of the [[Axilrod-Teller interaction]] see 
<ref>[http://dx.doi.org/10.1103/PhysRevA.45.3659 Phil Attard "Pair-hypernetted-chain closure for three-body potentials: Results for argon with the Axilrod-Teller triple-dipole potential", Physical Review A '''45''' pp. 3659-3669 (1992)]</ref>
<ref>[http://dx.doi.org/10.1103/PhysRevE.55.2707     J. A. Anta, E. Lomba and M. Lombardero "Influence of three-body forces on the gas-liquid coexistence of simple fluids: The phase equilibrium of argon", Physical Review E '''55''' pp. 2707-2712 (1997)]</ref>). 
However, the generic [[Lennard-Jones model]] has been frequently used due to its simplicity; some parameters are quoted in the next section. A specific interatomic potential for Ar has been proposed by Aziz 
<ref>[http://dx.doi.org/10.1063/1.466051  Ronald A. Aziz "A highly accurate interatomic potential for argon", Journal of Chemical Physics '''99''' p. 4518 (1993)]</ref>.

==Thermophysical properties (experimental) ==

{| border="1"
|- 
| Property  <ref>[http://www.webelements.com/argon/physics.html Physical properties of Argon on webelements]  </ref> || Temperature || Pressure
|-
| Triple point || 83.8058 K  || 69 kPa
|-
| Critical point || 150.87 K || 4.898 MPa
|-
| Melting point || 83.80 K ||
|-
| Boiling point ||87.30 K ||
|}

==Lennard-Jones parameters==
[[Image:Lennard-Jones.png|thumb| The Lennard-Jones  model for argon (Rowley, Nicholson and Parsonage parameters).]]
A selection of parameters for the [[Lennard-Jones model]] for liquid argon are listed in the following table:
{| border="1"
|- 
| Authors || <math>\epsilon/k_B</math> (K) || <math>\sigma</math>  (nm)|| Reference (year)
|-
| Rahman || 120   || 0.34  || <ref name="Rahman">  </ref> (1964)
|- 
|Barker, Fisher and Watts  ||142.095   ||  0.33605  || <ref>[http://dx.doi.org/10.1080/00268977100101821 J. A. Barker,  R. A. Fisher and R. O. Watts "Liquid argon: Monte carlo and molecular dynamics calculations", Molecular Physics '''21''' pp. 657-673 (1971)]</ref> (1971)
|- 
| Rowley, Nicholson and Parsonage || 119.8   || 0.3405  || <ref>[http://dx.doi.org/10.1016/0021-9991(75)90042-X   L. A. Rowley, D. Nicholson and N. G. Parsonage "Monte Carlo grand canonical ensemble calculation in a gas-liquid transition region for 12-6 Argon", Journal of Computational Physics  '''17''' pp. 401-414 (1975)]</ref> (1975)
|- 
| White   || 125.7   ||  0.3345    || <ref>[http://dx.doi.org/10.1063/1.479848 John A. White "Lennard-Jones as a model for argon and test of extended renormalization group calculations", Journal of Chemical Physics '''111''' pp. 9352-9356 (1999)]</ref> parameter set #4 (1999)
|}

==Buckingham potential==
The [[Buckingham potential]] for argon is given by (Eq. 27 <ref>[http://dx.doi.org/10.1098/rspa.1938.0173 R. A. Buckingham "The Classical Equation of State of Gaseous Helium, Neon and Argon", Proceedings of the Royal Society of London. Series A, Mathematical and Physical Sciences '''168''' pp. 264-283 (1938)]</ref>):
:<math>E(r) = 1.69 \times 10^{-8} e^{-r/0.273} -102 \times 10^{-12} r^{-6} </math>
where <math>E</math> is in ergs ( 10<sup>−7</sup> J) and <math>r</math> in &#8491;.
==BBMS potential==
The Bobetic-Barker-Maitland-Smith potential <ref>[http://dx.doi.org/10.1103/PhysRevB.2.4169 M. V. Bobetic and J. A. Barker "Lattice Dynamics with Three-Body Forces: Argon", Physical Review B '''2''' 4169-4175 (1970)]</ref> <ref>[http://dx.doi.org/10.1080/00268977100103181 G. C. Maitland and E. B. Smith "The intermolecular pair potential of argon", Molecular Physics '''22''' pp. 861-868 (1971)]</ref>.
==Radial distribution function==
[[Radial distribution function]]
*[http://dx.doi.org/10.1103/PhysRevA.7.2130 J. L. Yarnell, M. J. Katz, R. G. Wenzel and S. H. Koenig "Structure Factor and Radial Distribution Function for Liquid Argon at 85°K", Physical Review A '''7''' pp. 2130-2144 (1973)]
==Nucleation==
*[http://dx.doi.org/10.1063/1.3474945  Matthew J. McGrath, Julius N. Ghogomu, Narcisse T. Tsona, J. Ilja Siepmann, Bin Chen, Ismo Napari1, and Hanna Vehkamäki "Vapor-liquid nucleation of argon: Exploration of various intermolecular potentials", Journal of Chemical Physics '''133''' 084106 (2010)]
==Quantum simulations==
*[http://dx.doi.org/10.1080/00268978900100811 J. R. Melrose and K. Singer "An investigation of supercooled Lennard-Jones argon by quantum mechanical and classical Monte Carlo simulation", Molecular Physics '''66''' 1203-1214 (1989)]
==References==
<references/>
'''Related material'''
*[http://dx.doi.org/10.1080/00268976400100611 H. C. Longuet-Higgins and  B. Widom "A rigid sphere model for the melting of argon", Molecular Physics '''8''' pp. 549-556 (1964)]
*[http://dx.doi.org/10.1080/00268976800100721 D. Henderson and J. A. Barker "On the solidification of argon", Molecular Physics '''14''' pp. 587-589 (1968)]
*[http://dx.doi.org/10.1103/PhysRevA.5.2238  F. Lado "Numerical Calculation of the Density Autocorrelation Function for Liquid Argon", Physical Review A '''5''' pp. 2238-2244 (1972)]
*[http://dx.doi.org/10.1016/j.molliq.2009.09.009  Ali Asghar Davoodi and Farzaneh Feyzi "A new approach for long range corrections in molecular dynamics simulation with application to calculation of argon properties", Journal of Molecular Liquids '''150''' pp. 33-38 (2009)]

[[category: models]]
{{Numeric}}