Semi-empirical tight binding method for calculating energy levels of hydrogenated silicon nanoclusters as a function of size

A semi-empirical tight binding model is used for calculating energy levels of spherical hydrogenated silicon nanoclusters in the form of SimHn and two independent bases. The first basis is the nearest neighbor approximation of sp3s⁎ orthogonal basis and the second basis is the third nearest neighbor approximation of sp3 nonorthogonal basis. Also, bulk properties of silicon crystal are used in the calculations. As we expected, obtained results show that the change in the size of nanoclusters has a great influence on their energy levels. So optical properties of these nanoclusters can be controlled externally. A comparative study on the calculated results and experimental results also reveals a good agreement between the two approaches.