and an EAF of 20 ps -1 . HREM produced 16 ns on the target state, for a total of 128 ns or 192 ns of simulations. In a second series of HREM simulations on compounds 1 and 2, the scaling protocol was optimized in the first 1.6 ns by balancing the acceptance ratio on the fly using the iterative scheme of Eq. 4 (c = 2 and ω = 1/160 ps -1 with ten iteration cycles).