All λ windows were first energy minimized using steepest descent for 5000 steps, and then equilibrated in the canonical ensemble for 10 ps at 298.15 K. A production run of 10 ns per λ window was performed in the NPT ensemble at a pressure of 1 bar. The MD simulations were performed using the stochastic dynamics integrator at a timestep of 2 fs. The soft-core potential from Beutler et al. was applied to avoid instabilities in intermediate λ windows. Replica exchange swaps were attempted every 200 steps. Full details of simulation parameters can be found in the MDP files in the SI.