# Difference between revisions of "Test area method"

(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...) |
Carl McBride (talk | contribs) m (Slight correction of the equation.) |
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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 |

− | + | <ref>[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)]</ref> (Eq. 60): | |

− | + | :<math> \gamma = - \frac{ k_B T }{ \Delta {\mathcal A} } \ln \langle \exp(-\Delta U/k_B T)\rangle_0. </math> | |

+ | 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== | ==References== | ||

− | + | <references/> | |

+ | [[category: computer simulation techniques]] |

## Latest revision as of 17:21, 11 May 2009

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 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
^{[1]} (Eq. 60):

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.