Brownian motion of a free particle
The Langevin equation for a free particle is a model for the stochastic motion of a particle in a liquid or a gas for short times, and is
where is the particle velocity, is a drag coefficient, and is random noise. This is analogous to a massless particle in a harmonic potential, that's also a homework problem.
- 1. Using this analogy, what is , the velocity autocorrelation function?
- 2. Complete the code hw5/free_hints.py to calculate and plot as a function of time, assuming the particle at is at . Units have been chosen so the . What is the diffusion coefficient? Compare your results with the analytic solution for this problem, referenced in useful links that is here Links to an external site..