I modified the original algorithm to work better. It’s significantly slower but I get better results. There seems to be a relationship between number of objects in the unit cell and the algorithm’s performance. The more shapes the worse density. (more local minima on the landscape?). The other thing is packings are physically unrealistic, that is the shapes from different unit cells are intertwined. No more problem is that the density did go higher then 1 which should not be. Maybe we need a more suitable formula for computing density in the periodic setting.
Results
1 pentacene model in a unit cell
Density = 1.9932
2 pentacene models in a unit cell
Density = 1.0063
4 pentacene models in a unit cell
Density = 0.8093
8 pentacene models in a unit cell
Density = 0.6940
54 pentacene models in a unit cell
Density = 0.1788
