In tight-binding simulations interactions among particles are treated on the basis of quantum mechanics, being the electronic wave functions described as a linear combination of atomic orbitals. This enables writing the Schrödinger equation in matrix form. The components of the resulting Hamiltonian matrix are empirically fitted to correctly reproduce the physical properties of the system under study. This fitting procedure provides a semi-empirical character to this method, and limits the transferability of the defined Hamiltonian.
We have used tight-binding simulations for studying self-diffusion in amorphous silicon, which resulted in the identification of the relevant atomic rearrangement mechanisms and the evaluation of the activation energy for the diffusion process. We have also used tight-binding simulations for generating realistic models of the interface between crystalline and amorphous silicon.
Snapshots of representative atomic diffusion mechanisms found in amorphous silicon found through tight-binding molecular dynamics simulations (I. Santos et al., Phys. Rev. B 83, 153201 (2011) - Elucidating the atomistic mechanisms driving self-diffusion of amorphous Si during annealing).
|Classical molecular dynamics|
|Binary collision approximation|
|Kinetic Monte Carlo|