The front and back face is artificially breaked by introducing a degenerate zero-width facet (breaking line) at the optimal height sqrt(42) - 5 = 1.4807....
The subsequent evolution tends to widen this strip, signalling that this evolution is energetically better than the one without breakings. This is the situation at time 0.0025:
NOTE: to emphasize the breaking this picture does not use the computed quantities; the depth coordinate of the two parts of the front face (initially equal to 1) is exaggerated by using the formula: depth := 10*depth - 9. and similarly for the back face.
Here are the results at times 0.005, 0.0075, 0.01, 0.0125: