Alan Wolf

Chair of Physics

Dipole-Quadrupole interactions -- Scientific Programming

Cooper student Ernesto Colon wrote 3 simulations.
Each shows the interaction of a dipole (a pair of electric charges of equal magnitude and opposite sign) with either another dipole or a quadrupole (3 charges along a line with fixed separations: +q, -2q, +q).
In each case one of the charge distributions is 'glued' in place (stationary) and the other charge distribution is free to move and rotate.
The trajectories are determined by computing the electric forces of each charge on all of the others, and then numerically integrating Newton's 2nd Law with Runge-Kutta.

In the first simulation, below, two dipoles interact.  At some point the movable dipole collides with the stationary dipole and 
runs off the screen.  After the collision, the computation is not accurate. 

 In the second simulation, there is a slight change in the initial location of the movable dipole, and the trajectory is completely

 In the last simulation, the movable object is a quadrupole.