Chemical Thermodynamics 4.8 - Statistical Entropy

Short physical chemistry lecture on the calculation of entropy in statistical mechanics.

Using the partition function of the translations, rotations, vibrations, and electronic energy levels of a system of indistinguishable non-interacting molecules, we can derive an expression for the absolute entropy of any ideal gas of our choosing.

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[oiskipoiski]

Hello again :) I am starting to run some classical MD calculations and apparently the entropy we get from these simulations does not include any explicit translational, rotational, vibrational entopic contributions as discussed in the theory here. Can you maybe elaborate in what aspect my "thinking process" is wrong? During Classical Molecular dynamics simulations I only look at the average of all microstates right? Thank you for your help. :)

[oiskipoiski]

Thank you for the videos!! They help me a lot. At @1:45, how did you end up with that S equation and where does the derivative dlnQ/dT come from? Thank you

[oiskipoiski]

I have one follow up question: For Selec seems like it is the same equation for boltzmann entropy. In my understanding S= k*log (W) is the full entropy of the whole system, but why does Selec only partially contribute to the full entropy.
To summarize my question: We oftentimes see boltzman entropy equation as the equation for entropy (S= k *log(W)), but why in this video the Selec(which I think is the boltzman entropy equation) is only part of the whole entropy S?
Hopefully you understand my question :) Thank you