Density functional theory studies of quantum transport in molecular systems

Abstract

AbstractConventional semiconducting devices are rapidly approaching their physical limits, encouraging an increasing number of researchers across multiple disciplines to attempt to devise innovative ways to decrease the size and increase the performance of critical features in microelectronic circuits. One possible route is based on the idea of using molecules and molecular structures as functional electronic devices. While impressive experimental progress toward the realization of molecular electronics has been achieved, full insight into the potential for molecular‐based electronics requires accurate theoretical investigations of the processes governing their functioning. In the present study, we show that large‐scale quantum electronic structure calculations coupled with nonequilibrium Green function theory can be employed to determine quantum conductance on practical length scales. The combination of state‐of‐the‐art quantum mechanical methods, efficient numerical algorithms, and high‐performance computing allows for realistic evaluation of properties at length scales that are routinely reached experimentally. Two illustrations of the method are presented. First, we investigate the electron transport properties of a Si/organic‐molecule/Si junction, using a numerically optimized basis. Second, quantum chemical calculations using up to 104 basis functions are carried out to investigate amphoteric doping of carbon nanotubes by encapsulation of organic molecules. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006