Secondary instabilities form a codimension-2 point accompanied by a   homoclinic bifurcation
  A study of secondary instabilities in ac-driven electroconvection of a planarly aligned nematic liquid crystal is presented. At low frequencies one has a transition from normal rolls to a zig-zag pattern and at high frequencies a direct transition from normal to abnormal rolls. The crossover defines a codimension-2 point. This point is also the origin of a line of homoclinic bifurcations, which enable the transition from zig-zags to abnormal rolls at lower frequencies. 
S. Rudroff(1), H. Zhao(2), L. Kramer(2), I. Rehberg(1) ((1) Uni.   Magdeburg, Germany (2) Uni. Bayreuth, Germany)