1. Lecture 11b Polyatomic ideal gas
Model - translation, rotation, vibration
Rotational partition function
Vibrational partition function - harmonic oscillator
Thermodynamic functions
Problems

2. Single polyatomic molecule
Translational, rotational, vibrational and electronic energies additive
qt - evaluated last lecture
qr and qv - will evaluated today
Typically with De - binding energy

3. Translation Consider a single diatomic molecule is the box
M =m1+m2

4. Rotation Rotation energies: Degeneracy
r is the rotational temperature

5. Rotation - continuation
Unless temperature is very low:
If two atoms are the same we overcounted states by
 - symmetry number

6. Vibrations Vibrations - harmonic oscillator - frequency
Near potential minimum
With reduced mass

7. Vibrations - continuation
Partition function
Vibrational temperature

8. Partition function Q and free energy F
translation rotation
vibrations electronic

9. Energy
translation rotation
vibrations electronic

10. Heat capacity
Translation rotation vibrations

11. Chemical potential