  We numerically investigate the phenomenological nonlocal Ginzburg-Landau
Hamiltonian for two-dimensional superconductors in a strong magnetic field by
Langevin equation. We obtain a regular vortex lattice which is very near to the
square lattice. We calculate the structure factor and Abrikosov factor at
various temperatures. We also evaluate the specific heat and obtain a cusp
which indicates the melting of the vortex lattice.
