## Abstract

Calculations for optical excitations in confined systems require knowledge of the inverse screening dielectric function [Formula presented], which plays a crucial role in determining exciton binding energies. We present a new efficient real-space method of inverting and storing large ab initio dielectric matrices of confined systems, which relies on the separability of [Formula presented] matrix in [Formula presented] and [Formula presented]. The method has allowed, for the first time, full ab initio calculation of [Formula presented] of dimension [Formula presented], and for quantum dots as large as [Formula presented]. The effective screening in Si quantum dots up to 1.1 nm in diameter is found to be very ineffective with average dielectric constants ranging from 1.1 to 1.4.

Original language | English (US) |
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Pages (from-to) | 127401/1-127401/4 |

Number of pages | 1 |

Journal | Physical Review Letters |

Volume | 90 |

Issue number | 12 |

DOIs | |

State | Published - Jan 1 2003 |

### Bibliographical note

Funding Information:This work was supported by the Computational Materials Science Network of the Department of En?>ergy, the National Science Foundation, and the Minne?>sota Supercomputing Institute.