Dynamic Approach to the Ground State of Vortex System withRandom Pinning

We study the ground state of a two-dimensional vortex system with random pinnings by cooling the vortex system to zero temperature. The peak of structure factor S(k) of vortices increases with vortex density B but decreases with pin density B_Ф, indicating that the vortex lattice becomes better and better ordered with increasing B. When B > B_Ф, the triangular vortex lattice is observed away from the pins. Repulsive vortex interactions destroy the Mott insulator phase which is predicted to occur at B = B_Ф. The crossover line between the strong Bose glass and the weak Bose glass is nearly independent of B_Ф for small B_Ф.