Editing Internal energy

The '''internal energy''' is given by 

:<math>U=-T^2 \left. \frac{\partial (A/T)}{\partial T} \right\vert_{N,V} = k_B  T^{2} \left. \frac{\partial \log Z(T)}{\partial T} \right\vert_{N,V}</math>

where <math>A</math> is the [[Helmholtz energy function]] and <math>Z</math> is the [[partition function]].
[[category: statistical mechanics]]
@@ Line 1: / Line 1: @@
-The '''internal energy''' of a system is given by the sum of the kinetic energy and the
+The '''internal energy''' is given by
-potential energy. This excludes the external energy of the system, for example motion of the center of mass of the system, or the presence of an external field.
-The internal energy in [[classical thermodynamics]] is given by
-:<math>\left. U \right.=TS-pV</math>
-and in [[statistical mechanics]] by
 :<math>U=-T^2 \left. \frac{\partial (A/T)}{\partial T} \right\vert_{N,V} = k_B  T^{2} \left. \frac{\partial \log Z(T)}{\partial T} \right\vert_{N,V}</math>