V is the volume of the simulation box, k B is Boltzmann's constant, T is the temperature in Kelvin, which is set to 298K here, and the angular brackets indicate a classical ensemble average. Eq. ( ) is in cgs units and is valid with conducting boundary conditions. ⟨ ⃗ M ⟩ is nearly zero if enough configurations are used to compute the ensemble average. The IR spectrum of liquid water can be computed from