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.

Illustration of the presence of GeS_4 tetrahedra in the GeS_2 material's family. a) GeS_4 tetrahedra, representations b) of the \alpha-GeS_2 crystal and c) of the GeS_2 glass using tetrahedra. — **Figure 5.9:** Illustration of the presence of GeS $_{4}$ tetrahedra in the GeS $_{2}$ material's family. a) GeS $_{4}$ tetrahedra, representations b) of the $α$ -GeS $_{2}$ crystal and c) of the GeS $_{2}$ glass using tetrahedra.

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.

**Figure 5.10:** Corner sharing (left) and edge sharing (right) tetrahedra.