In enhanced MSMD simulations looking for the benzene binding site, the protein was solvated in a 0.5 M benzene and water solution. The GCMC sphere was centered on the middle of the protein at the midpoint between the CA atoms of Phe104 and Glu11 with a radius of 26.5 Å to cover the whole protein. The infinitely dilute excess chemical potential of benzene was taken to be -0.68 kcal mol -1 calculated as described above. The average volume per ligand was taken as 3321 Å3 to define a concentration of 0.5 M (Eq. 4). Using a switching time of 50 ps, we ran six repeats of 700 GCNCMC/MD cycles (1 move per 50 ps of MD) with the first 200 cycles discarded as equilibration, giving a maximal simulation time of 50 ns (25 ns of MD with 25 ns of switches). For a fair comparison, GCNCMC simulations were compared to 50 ns simulations of conventional NPT MD on the same system.