Next, we consider each driving force in the overdamped Langevin equation. First, we describe the random force 𝑭 𝐵 . The random force 𝑭 𝐵 follows a Gaussian distribution in thermal equilibrium, and the displacement distribution due to the random force also follows a Gaussian distribution. Therefore, the random displacement due to Brownian motion Δ𝒓 𝐵 = (Δ𝑥 𝐵 , Δ𝑦 𝐵 , Δ𝑧 𝐵 ) over short time step Δ𝑡 is given by