An efficient graphics processing units (GPUs) version of time-dependent 
wavepacket code is developed for the atom-diatom state-to-state reactive 
scattering processes. The propagation of the wavepacket is entirely calculated 
on GPUs employing the split-operator method after preparation of the initial 
wavepacket on the central processing unit (CPU). An additional split-operator 
method is introduced in the rotational part of the Hamiltonian to decrease 
communication of GPUs without losing accuracy of state-to-state information. The 
code is tested to calculate the differential cross sections of H + H2 reaction 
and state-resolved reaction probabilities of nonadiabatic triplet-singlet 
transitions of O((3)P,(1)D) + H2 for the total angular momentum J = 0. The 
global speedups of 22.11, 38.80, and 44.80 are found comparing the parallel 
computation of one GPU, two GPUs by exact rotational operator, and two GPU 
versions by an approximate rotational operator with serial computation of the 
CPU, respectively.