Abstract
The morphology of needle shaped crystals is, usually, ill-predicted
when using the common attachment energy approach. Here we explain the needle
shape of triacylglycerol crystals on the basis of a two-dimensional nucleation
growth mechanism. For that the edge energies of 2D nuclei on the surfaces
of the various crystal faces is determined and turns out to be much lower
than expected when applying the attachment energy criteria. The edge energies
are found by determining the connected nets of the various faces that follow
from the crystal structure and the interaction energies between the molecules.
The results are confirmed by Monte Carlo simulations.