Thermal Langevin force normalization
= Thermal Langevin force normalization
For $m\dot v_i=-\zeta v_i+\xi_i$, classical equilibrium <white noise> satisfies $\langle\xi_i(t)\xi_j(t')\rangle=2\zeta k_BT\delta_{ij}\delta(t-t')$. The normalization produces the equipartition velocity variance $k_BT/m$.