Point Defects in Si A Case Study

One of our recurring themes has been the capacity to examine a particular question from a number of different energetic perspectives. In broadest terms, we have divided our theoretical perspectives along the lines of whether or not they reflect a vision of the defected solid as a continuum or as a discrete collection of atoms. However, as we have discussed in detail already, even within the picture of a crystalline solid as a collection of atoms, it is possible to consider widely different frameworks for the total energy. In the present section, we use Si as a case study in order to contrast empirical and first-principles approaches to point defects as was done already for metals. 

Stillinger-Weber Tersoff Tight-Binding LDA Expt. 

Because of the difficulties that have already been noted with respect to the transferability of empirical potentials for Si, there has been tremendous pressure to seek alternative schemes which are at once more accurate and still represent a reduction in the computational burden associated with first-principles calculations. In the context of Si in particular, a powerful alternative is offered by tight-binding analysis. Like in the case of the empirical potentials, there are a number of different schemes and fits, each with its own particular patriots and warriors. On the other hand, the basic ideas don t really differ from what has been spelled out in chaps. 3 and 4. 

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