Energy equation: Difference between revisions

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(New page: The '''energy equation''' is given by :<math>\frac{U^{\rm ex}}{N}= \frac{\rho}{2} \int_0^{\infty} \Phi(r)~{\rm g}(r)~4 \pi r^2~{\rm d}r</math> where <math>\Phi(r)</math> is a ''central'' ...)
 
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The '''energy equation''' is given by  
The '''energy equation''' is given, in [[classical thermodynamics]], by  
 
:<math>\left. \frac{\partial U}{\partial V} \right\vert_T  = T \left. \frac{\partial p}{\partial T} \right\vert_V -p  </math>
 
and in [[statistical mechanics]] it is obtained via the [[thermodynamic relations | thermodynamic relation]]
 
:<math>U = \frac{\partial (A/T)}{\partial (1/T)}</math>
 
and making use of the [[Helmholtz energy function]] and the canonical [[partition function]] one arrives at
 
:<math>\frac{U^{\rm ex}}{N}= \frac{\rho}{2} \int_0^{\infty} \Phi(r)~{\rm g}(r)~4 \pi r^2~{\rm d}r</math>
:<math>\frac{U^{\rm ex}}{N}= \frac{\rho}{2} \int_0^{\infty} \Phi(r)~{\rm g}(r)~4 \pi r^2~{\rm d}r</math>
where <math>\Phi(r)</math> is a ''central'' potential, <math>U^{\rm ex}</math> is the  
where <math>\Phi(r)</math> is a ''two-body central'' potential, <math>U^{\rm ex}</math> is the  
excess [[internal energy]] per particle,  and <math>{\rm g}(r)</math> is the [[pair distribution function]].
[[excess internal energy]] per particle,  and <math>{\rm g}(r)</math> is the [[radial distribution function]].
[[category:statistical mechanics]]
[[category: classical thermodynamics]]

Latest revision as of 14:31, 29 June 2007

The energy equation is given, in classical thermodynamics, by

and in statistical mechanics it is obtained via the thermodynamic relation

and making use of the Helmholtz energy function and the canonical partition function one arrives at

where is a two-body central potential, is the excess internal energy per particle, and is the radial distribution function.