  Systemic symmetry is introduced into our work to investigate the symmetries
of different ZnO nanocrystals. Result shows that systemic symmetries obey the
law of spontaneous symmetry breaking during the formation of ZnO nanocrystals.
A unitary formation mechanism of ZnO nanocrystals is proposed accordingly. Our
results provide new insight into both crystallization and spontaneous symmetry
breaking at meso-scale.
