After constructing and minimizing the simulation box, the system is equilibrated by subsequent 2 ns of N V T simulation (using the modified Berendsen-velocity rescale-thermostat with a time constant for coupling of 0.1 ps to keep the temperature constant at 298.15 K) followed by 15 ns of N pT simulation. Production trajectories were then extended for a total of 100 ns, adopting a N pT ensemble at 298 K and 1 atm. The Nose-Hoover thermostat and the Parrinello-Rahman barostat were used in the N pT simulations with relaxation times of 1.0 and 5.0 ps, respectively. Configurations used in the subsequent analysis were extracted from the MD trajectory every 1 ps.