The nature of the chemical bonding from the density of states

Here we will explain how to determine the nature of the chemical bond from the density of states DOS.

We take the example of the compound Bi2S3

The chemical bonding character of Bi2S3 can also be studied from the density of the states. From the partial densities of the figure above, it is clear that the main mechanism of the chemical bond is the hybridization between the 6p states of Bi and the 3p states of S. The chemical bond has a covalent character and ionic at the same time, covalent because the 6p states of Bi and the 3p states of S are strongly hybridized and degenerate over a large part of their extension, and ionic since the relative quantity of the 6p states of Bi and the 3p states of S is different below and above Fermi level. Below the Fermi level, the 3p states of S dominate and above Fermi level, the 6p states of Bi dominate.