Thursday, May 19, 2011

Peer instruction: radial distribution functions

These slides show questions I used when teaching radial distribution functions using peer instruction. The slides are in Danish, but I hope you get the idea and there is always Google translate. Any questions, just leave a comment.

Some comments about specific slides:
Slide 8: The hint is given after the first vote.

Slides 11-18 show results from two Molecular Workbench exercises, which you can download here and here, once you have installed Molecular Workbench on your computer.

Slide 11: First I run the solid simulation, then pose the question and have a couple of votes, then click on the "show pair correlation function" in the MW simulation.  Note that you have to run for at least 100,000 fs to get good statistics (i.e. relatively smooth curves).  Then I explain the answer (slides 12 and 13)

Slide 14: Same procedure as slide 11, but for the liquid.

Slide 16: No vote, since the answer is pretty obvious, but I do ask where the peak at r = ~1.5 Å comes from.  Of course it comes from the attractive part of the Lennard-Jones potential, and you can clearly see some particles sticking together in the gas simulation.  To check, I change the depth of the well from 0.1 eV to 0.001 eV (simply double-click on any of the particles, and you will see what to do), re-run the simulation, and show the radial distribution function (summarized in slide 17).

See all posts related to peer instruction here.
Post a Comment