The example shows how to generate structures, used in paper:
Cadars, S., Ho Ahn, N., Okhotnikov, K., Shin, J., Vicente, A., Bong Hong, S., & Fernandez, C. (2017). 
Modeling Short-Range Substitution Order and Disorder in Crystals: Application to the Ga/Si Distribution 
in a Natrolite Zeolite. Solid State Nuclear Magnetic Resonance. 
http://doi.org/10.1016/j.ssnmr.2017.04.001
