Parallelized QM/MC simulations applied to the Diels-Alder reaction in aqueous, methanol and propane solutions

An algorithm to parallelize the Metropolis sampling was devised and applied to the Monte Carlo simulations using quantum mechanical calculations (QM/MC simulations). As a 4 CPU calculation needs 670 000 s to finish the same QM/MC simulation with the parallelized program, the present algorism reduced the computational time to almost half as long as that of one CPU calculation. The parallelized QM/MC simulation was applied to Diels-Alder reactions between methylvinylketone and cyclopentadiene. The QM/MC (B3LYP/6-311++G∗∗//MP2/6-31G∗,PM3) calculation gave averaged activation energies of 12.7, 13.8 and 15.2 kcal mol−1 in aqueous, methanol and propane solutions. These results are well consistent with those observed.