  We accelerated an ab-initio molecular QMC calculation by using GPGPU. Only
the bottle-neck part of the calculation is replaced by CUDA subroutine and
performed on GPU. The performance on a (single core CPU + GPU) is compared with
that on a (single core CPU with double precision), getting 23.6 (11.0) times
faster calculations in single (double) precision treatments on GPU. The energy
deviation caused by the single precision treatment was found to be within the
accuracy required in the calculation, \sim 10^{-5} hartree. The accelerated
computational nodes mounting GPU are combined to form a hybrid MPI cluster on
which we confirmed the performance linearly scales to the number of nodes.
