  We describe effects of anisotropy caused by the crystal lattice in d-wave
superconductors using effective free energy approach in which only one order
parameter, the d-wave order parameter field, is used. All the effects of
rotational symmetry breaking, including that of the s-wave mixing, can be
parametrized by a single four derivative term. We find solutions for single
vortex and the vortex lattice. Extending the formalism to include the time
dependence, effects of anisotropy on moving vortex structure are calculated.
Both direct and Hall I-V curves as functions of the angle between the current
and the crystal lattice orientation are obtained.
