Fig. 6.

(a) log P_v as a function of $(N-\langle N\rangle )/\sqrt{\langle \delta N^2\rangle }$ for a cube of side 1.2 nm, calculated in the NPT ensemble, over a range of pressures at T = 300 K. (b) Free energy, μ^ex, of the same cube as a function of pressure. A linear fit yields the excess volume of the cavity, v^ex ≈ 0.67v.