  Structure and dynamics of penta-hepta defects in hexagonal patterns is
studied in the framework of coupled amplitude equations for underlying plane
waves. Analytical solution for phase field of moving PHD is found in the far
field, which generalizes the static solution due to Pismen and Nepomnyashchy
(1993). The mobility tensor of PHD is calculated using combined analytical and
numerical approach. The results for the velocity of PHD climbing in slightly
non-optimal hexagonal patterns are compared with numerical simulations of
amplitude equations. Interaction of penta-hepta defects in optimal hexagonal
patterns is also considered.

Pattern Formation and Solitons;Pattern Formation and Solitons