Difference between revisions of "Test area method"

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(New page: Related to the test volume method for the pressure (which, in turn, is related to Widom test-particle method). The surface tension of a planar interface is given by the cha...)
 
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Related to the [[test volume method]] for the pressure (which, in turn, is related to [[Widom test-particle method]]). The [[surface tension]] of a planar [[interface]] is given by the change in [[internal energy]] <math>\Delta U</math> caused by "squeezing" the system: modifying both the length in the direction normal to the interface and the area in the plane of the interface, in such a way that the total volume is left unchanged.
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The '''test area method''' is related to the [[test volume method]] for the calculation of the [[pressure]] (which, in turn, is related to [[Widom test-particle method]]). The [[surface tension]] of a planar [[interface]] is given by the change in [[internal energy]] <math>\Delta U</math> caused by "squeezing" the system: modifying both the length in the direction normal to the interface and the area in the plane of the interface, in such a way that the total volume is left unchanged.
  
 
It can be shown that the surface tension, if the changes are small, is given by:
 
It can be shown that the surface tension, if the changes are small, is given by:
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==References==
 
==References==
 
#[http://dx.doi.org/10.1063/1.2038827    Guy J. Gloor, George Jackson,    Felipe J. Blas and Enrique de Miguel    "Test-area simulation method for the direct determination of the interfacial tension of systems with continuous or discontinuous potentials", Journal of Chemical Physics '''123''' 134703 (2005)]
 
#[http://dx.doi.org/10.1063/1.2038827    Guy J. Gloor, George Jackson,    Felipe J. Blas and Enrique de Miguel    "Test-area simulation method for the direct determination of the interfacial tension of systems with continuous or discontinuous potentials", Journal of Chemical Physics '''123''' 134703 (2005)]
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[[category: computer simulation techniques]]

Revision as of 12:47, 7 February 2008

The test area method is related to the test volume method for the calculation of the pressure (which, in turn, is related to Widom test-particle method). The surface tension of a planar interface is given by the change in internal energy \Delta U caused by "squeezing" the system: modifying both the length in the direction normal to the interface and the area in the plane of the interface, in such a way that the total volume is left unchanged.

It can be shown that the surface tension, if the changes are small, is given by:

 \gamma  =  - \frac{ k_B T  \Delta A } \log\langle \exp(-\Delta U/k_B T)\rangle.

The expression parallels the one for the pressure in the test volume method; the advantages of this technique are also similar: avoidance of force calculation, easiness for discontinuous potential...

References

  1. Guy J. Gloor, George Jackson, Felipe J. Blas and Enrique de Miguel "Test-area simulation method for the direct determination of the interfacial tension of systems with continuous or discontinuous potentials", Journal of Chemical Physics 123 134703 (2005)