On the left is a collection of 32 electrons, initially clustered near the origin of real space. On the right is the same set of electrons in velocity space, distributed in velocity according to a Maxwellian distribution.
Click on run or hit the spacebar to see the time evolution of the system in absence of any applied fields. The program leaves the display on the screen for several time steps so you will see a short segment of the trajectory of the electrons. (We will refer to these as worms.) The average position of the electrons in BOTH spaces is indicated by the large green dot; the origin by the red dot.
In real space, the trajectories are straight lines, with sudden changes in direction at each scattering event. In velocity space, the velocities remain fixed (no applied fields) between scatterings, and the electron moves at the time of scattering to a new point. A few of the electrons are colored so that you can correlate the change in trajectory direction on the left with the change of location on the right.
Use the temperature slider to reduce the temperature from 300 K to 3 K to see the effect of cooling the electron gas.
Click on the two show graph toggles and drag the graphs to convenient locations. One shows the mean square deviations of the x- and y- components of the electron velocities from their mean. Change the temperature by x10 and check the magnitude of the change.
The other is the mean square deviations of the positions. With T=300K, interpret this plot after the program has run for a while.