First-principles Investigation of CdSe Nanowires using Wannier functions:Effects of Surface and Confinement on dielectric properties

Understanding how the electronic properties of a material change at the nanoscale is important for a wide range of technological applications as well as for basic science. One-dimensional nano-structures such as nanowires hold great promise for their potential application in opto-electronic devices. In this work, we investigate the electronic polarity behavior and transverse polarizability of hexagonal Cadmium Selenide (CdSe) nanowires of up to 3 nm in diameter, using a Wannier function description from density functional theory calculations. We address effects of quantum confinement and surfactant molecules on these nanowire properties via a local property analysis using the Wannier functions, revealing a few interesting insights in terms of local polarity changes. Interestingly, the transverse polarizability is enhanced and deviates significantly from the classical model for a dielectric cylinder at this scale. We will discuss our observation in terms of surface and confinement effects.