  The accurate and efficient calculation of the rate coefficients of chemical
reactions is a key issue in the research of chemical dynamics. In this work, by
applying the dimension-free ultra-stable Cayley propagator, the thermal rate
coefficients of a prototypic high dimensional chemical reaction OH + CH4 -> H2O
+ CH3 in the temperature range of 200 K to 1500 K are investigated with ring
polymer molecular dynamics (RPMD), on a highly accurate full-dimensional
potential energy surface. Kinetic isotope effects (KIEs) for three
isotopologues of the title reaction are also studied. The results demonstrate
excellent agreement with experimental data, even in the deep tunneling region.
Especially, the Cayley propagator shows high calculation efficiency with little
loss of accuracy. The present results confirmed the applicability of the RPMD
method, particularly the speed-up by Cayley propagator, in theoretical
calculations of bimolecular reaction rates.
