Multiband transmission calculations for nanowires using an optimized renormalization method

The discovery of an interesting nanostructure behavior or the design of useful nanodevices requires state-of-the-art physical models. Realistic, multiband nanowire calculations especially tend to be computationally intensive and slow. Here, we develop optimizations to the renormalization method of Grosso [Phys. Rev. B 40, 12328 (1989)] specifically for nanowires with [100]- or [111]-oriented axes. For no-spin-orbit models, our optimizations give far superior performance to other available methods, while for spin-orbit models on a single processor, our results are at least as good as the best alternative. More importantly, the parallel scalability of our optimizations is superior to that of other available methods, making optimized renormalization very attractive for multiple-processor computers. We demonstrate the method with calculations for Si nanowires.