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NobodyMinus
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Homework Statement
5. The nuclei of atoms in a certain crystalline solid have spin one. Each nucleus can be in anyone of three quantum states labeled by the quantum number m, where m = −1,0,1. This quant number measures the projection of the nuclear spin along a crystal axis of the solid. Due to the ellipsoidal symmetry, a nucleus has the same energyε for in the state m = −1 and the state m = 1, compared with an energy E = 0 in the state of m = 0.
(a) Find an expression as a function of T of the nuclear contribution to the average internal energy of the solid
per mol.
(b) Find an expression as a function of T of the nuclear contribution to the entropy of the solid per mol
Homework Equations
U=∑EiPi
Pi=[itex]e^{-Ei/kT}/Z[/itex]
Z=∑[itex]e^{-Ei/kT}[/itex]
Where the sums are over all available states
The Attempt at a Solution
I solved part a by using the first equation and solving for Z. I got
Z=[itex]1+2e^{-ε/kT}[/itex]
U=[itex]\frac{2ε}{2+e^{ε/kT}}[/itex]
To get the energy per mole as a function of temperature, I simply multiplied by Avagadro's number
[itex]\frac{U}{mol}[/itex]=[itex]\frac{2εN_{A}}{2+e^{ε/kT}}[/itex]
From here, I get stuck trying to find entropy as a function of T. I'm not quite certain what to do. I've tried S=[itex]\int TdU[/itex] but it gives me a gruesome mess that can't be solved analytically by Mathematica. Any suggestions?
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