  This paper describes some applications of GPU acceleration in ab initio
nuclear structure calculations. Specifically, we discuss GPU acceleration of
the software package MFDn, a parallel nuclear structure eigensolver. We modify
the matrix construction stage to run partly on the GPU. On the Titan
supercomputer at the Oak Ridge Leadership Computing Facility, this produces a
speedup of approximately 2.2x - 2.7x for the matrix construction stage and 1.2x
- 1.4x for the entire run.
