An embedding scheme based on quantum linear-scaling methods

We point out a close connection between linear-scaling electronic structure techniques and the embedding problem (treatment of a defect in an infinite perfect crystal), the key to the connection being the locality of the density matrix. We show how an existing linear-scaling technique can be turned into an embedding technique, which appears to have advantages over earlier methods. The effectiveness of the new technique is illustrated by practical tight-binding calculations on three systems: a substitutional impurity and the vacancy in silicon, and the Si (0 0 1) surface. We indicate the developments needed to perform embedding calculations by the new approach with first-principles density-functional theory (DFT).