# Proportion of tetrahedral links and units in the structure model

Often the structure of a material is represented using building blocks. One of the the most frequently occurring building blocks are tetrahedra. Figure 5.9 shows a model of GeS$$_2$$ materials using GeS$$_4$$ tetrahedra as building blocks.

Atomes computes the fraction of the different tetrahedra in materials, the distinction between these tetrahedra being made on the nature of the connection between each of them. Tetrahedra can be linked either by corners or edges [Fig. 5.10], Atomes computes the fraction of atoms forming tetrahedra as well as to the fraction of linked tetrahedra.