Electronic Structure Calculations for Graphene based NEMS
I do research in the area of computational nano-physics, where I perform extensive calculations applied on nano-sized materials. My focus is on modeling and simulating Nanoelectromechanical systems (NEMS); which are devices combining electrical and mechanical functionality at the nanoscale. For example, one would like to integrate logic devices which can be manipulated electronically, with mechanical entities such as pumps or motors. An exciting application is lab-on-a-chip solutions at the nanoscale, which would enable complex chemical manipulation and analysis of extremely small samples (perhaps just a few molecules) of, e.g., DNA. other example, is an on going project, I am working on, where I test the capability of Graphene to act as an effective humidity sensor; where the electronic structure properties are changing in a sense related to the humidity percentage. Carbon-based materials such as carbon nanotubes and graphene are extremely promising materials for NEMS technology since their properties in many respects directly meet the needs. For instance, a large Young's modulus is vital to the stability of NEMS. Further, their low friction makes possible a range of mechanical solutions such as frictionless mechanical bearings. At the same time, carbon materials exhibit the relevant electrical properties making them suitable as base materials for transistors and other electronic components. An integral part of NEMS operation is the mechanical functionality. Thus mechanical and acoustical modelling is necessary in order to optimize the design of graphene-based NEMS. Since graphene is not a bulk material but uniquely two-dimensional, its mechanical properties cannot be modelled with conventional continuum software, but it becomes necessary to employ extensive computational methods that take into account the quantum-mechanical nature of these materials. These simulation codes should enable for HPC capabilities and should be extensible, thus, researchers can tailor it in order to adapt with their research requirements. In this project, the aim is to elucidate the mechanical and acoustical properties of graphene, graphene-derived materials and the boundaries to the anchors in NEMS using state-of-the-art first-principles methods based on density functional theory (DFT). The work will be carried out in close collaboration with leading indoor experimentalists in the field within our department. At the moment (2014), we are investigating the possibility of using graphene as a humidity sensor. The changes in the electronic structure properties of the graphene sheet have been evaluated in the presence of water as well as the accompanying substrate. The electronic and structural properties of the system have been studied by means of ab-initio calculations based on density functional theory (DFT) that allows for investigations in a speedy, accurate and efficient way. In particular, we focus our attention to investigate the effects of defects in the substrate and how it influence the properties. Update: at this moment, I am examining different graphene based devices response towards different gas sensing. (H2O, CO2, CO, NO, NO2, NH3) 2016 updates: I am working on transport calculations.