The electronic band structure of a material is a representation of the energy levels of electrons in a crystalline solid as a function of their momentum. It is a crucial property that determines the electrical, optical, and thermal properties of the material. Density functional theory DFT is a widely used computational method to study the electronic structure of materials.When the lattice parameters the size and shape of the unit cell of a material are varied, the electronic band structure can change significantly. This is because the lattice parameters determine the periodic potential experienced by the electrons in the crystal, which in turn affects their energy levels and wavefunctions. The changes in the electronic band structure can lead to different material properties, such as changes in conductivity, optical absorption, or even phase transitions.Using DFT, one can systematically study the effect of varying lattice parameters on the electronic band structure of a material. The key steps involved in such a study are:1. Choose a range of lattice parameters to investigate. This can be done by either varying the lattice constants a, b, and c or the lattice angles , , and or both.2. For each set of lattice parameters, perform a DFT calculation to obtain the optimized atomic positions and the electronic band structure. This involves solving the Kohn-Sham equations self-consistently for the given lattice geometry and potential.3. Analyze the changes in the electronic band structure as a function of the lattice parameters. This can involve comparing the band gaps, the positions of the valence and conduction bands, the effective masses of the charge carriers, and the nature of the electronic states e.g., whether they are localized or delocalized .4. Relate the changes in the electronic band structure to the changes in the material properties. This can be done by calculating the density of states, optical absorption spectra, or transport properties as a function of the lattice parameters.By following these steps, one can gain insights into how the electronic band structure and the associated material properties are affected by the lattice parameters. This information can be valuable for designing materials with specific properties or for understanding the underlying mechanisms behind observed experimental trends.