Lennard-Jones model: Difference between revisions

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* Temperature; <math> T^* \equiv k_B T/\epsilon </math>, where <math> T </math>  is the absolute temperature and <math> k_B </math> is the [[Boltzmann constant]]
* Temperature; <math> T^* \equiv k_B T/\epsilon </math>, where <math> T </math>  is the absolute temperature and <math> k_B </math> is the [[Boltzmann constant]]
==Argon==
==Argon==
The Lennard-Jones parameters for argon are <math>\epsilon/k_B \approx</math>  120 K and <math>\sigma \approx</math>  0.34 nm.
The Lennard-Jones parameters for argon are <math>\epsilon/k_B \approx</math>  119.8  K and <math>\sigma \approx</math>  0.3405 nm. (Ref. ?)
[[Image:Lennard-Jones.png|center]]
[[Image:Lennard-Jones.png|center]]
This figure was produced using [http://www.gnuplot.info/ gnuplot] with the command:
This figure was produced using [http://www.gnuplot.info/ gnuplot] with the command:

Revision as of 16:24, 22 March 2007

The Lennard-Jones potential is given by

where:

  • Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle V(r) }  : potential energy of interaction between two particles at a distance r;
  • Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \sigma }  : diameter (length);
  • Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \epsilon }  : well depth (energy)

Reduced units:

  • Density, Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \rho^* \equiv \rho \sigma^3 } , where (number of particles Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle N } divided by the volume Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle V } .)
  • Temperature; Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle T^* \equiv k_B T/\epsilon } , where Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle T } is the absolute temperature and Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle k_B } is the Boltzmann constant

Argon

The Lennard-Jones parameters for argon are Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \epsilon/k_B \approx} 119.8 K and Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \sigma \approx} 0.3405 nm. (Ref. ?)

This figure was produced using gnuplot with the command:

plot (4*120*((0.34/x)**12-(0.34/x)**6))

References

  1. J. E. Lennard-Jones, "Cohesion", Proceedings of the Physical Society, 43 pp. 461-482 (1931)