Large-Scale First-Principles Electronic Structure Calculations for Silicon Nanostructures

We have performed large-scale first-principles calculations for Si nanostructures constructing from 1000 ∼ 10,000 atoms by employing a massively parallel computer. As examples of practical applications, we show the results of the calculated electronic structures for nanometer-size Si quantum dots and Si nanowires. As the size of the systems becomes larger, the band structure becomes more complex. However, in the extremely large size limit, the electronic structure becomes rather simple, so that one can easily understand it by simple electrostatics or effective mass theory.