The gyrokinetic toroidal code (GTC) is a massively parallel, particle-in-cell code for turbulence simulation in support of the burning plasma experiment ITER, the crucial next step in the quest for fusion energy. GTC is the production code for the multi-institutional US Department Of Energy (DOE) Scientific Discovery through Advanced Computing (SciDAC ) project, ISEP Center (Integrated Simulation of Energetic Particle in Burning Plasmas) GTC simulation of the turbulence self-regulation by zonal flows was published in a 1998 Science paper, which is one of the most cited magnetic fusion research paper.