报告摘要:   Ab initio methods based on density functional theory (DFT) and non-equilibrium Green functions  (NEGF) are an increasingly popular approach to transport properties of nanoscale systems. SMEAGOL1 is an efficient implementation of such methods, which uses the Hamiltonian provided by the DFT code SIESTA and employs NEGF to calculate the density matrix, transmission coefficients and I-V characteristics. Over 100 groups worldwide have used SMEAGOL to perform simulations of molecular-electronic and graphene-based systems, including insulating and conducting molecules between magnetic, non-magnetic or superconducting leads and molecules encapsulated in carbon nanotubes. As examples of SMEAGOL-based calculations, in this talk I shall discuss a range of geometrical methods for controlling electron transport through single molecules, including:

• ring rotations in conjugated molecules;
• varying the angle of contact to conducting electrodes2
• rotating the magnetic moments of carbon-nanotube-encapsulated molecules3.
• Fano resonances associated with side groups attached to rigid backbones4;
• solvation shells of analyte molecules in the vicinity of a conducting backbone5;
 As well as the control of electrical currents via geometry, the inverse effect is discussed, whereby the geometry of a nanoscale conductor is controlled an electrical current. This is exemplified by carbon-nanotube windmills6, whereby an electrical current causes an inner chiral tube of a double-wall nanotube to rotate.

报告人简介：Current activity and discipline
Research activities include interdisciplinary projects, in spintronics, carbon-based electronics, molecular
electronics and quantum computing.
           Principal accomplishments
During his early career in Lancaster he published a number of highly-cited papers on quasi-particle dynamics in superconductors and has subsequently generalized these methodologies to yield a new state-of-the-art capability (SMEAGOL) for ab initio transport through magnetic multilayers, carbon nanotubes, single molecules and nanoscale spintronic devices.