DFT Investigation Of Energy Structures And Device Characteristics On Precious Metals Au,Ag And Pt

The investigation of nano atomic/molecular devices is quite important for the progress of information technology,by which the human society will break through the classical limit and arrive in quantum age.Density functional theory?DFT?is an effective method to solve the ground state energy of a many-body electron system.By combining with non-equilibrium Green's functions,DFT can deal with those electron transport problems containing hundreds atoms.This paper introduces a systematic investigation on the energy level structure and device characteristics of precious metals Au,Ag and Pt,by using DFT code SIESTA and transport code smeagol?Their I-V curve,spin polarization,DOS,PDOS,transmission coefficients are analysed,and the variations of charge,bond length and bond energy are also discussed.This thesis includes such aspects of research works as follows.The transport calculation with and without spin correction of C₆₀,Au@C₆₀and Ag@C₆₀,illustrates the importance of spin resonant transmission mechanism to the system transport characteristics.Compared with the spin transport properties of a Au@C₆₀with side set endohedral Au atom,the actual application prospect of spin molecule devices is also discussed.The transport properties of S-Au-S junction and Au-Au-Au junction in different anchor distances,make a further understanding of the spin resonant transmission mechanism.The anchor chemical bond affects the transport mechanism of the center Au atom,and the energy shifts of the anchor atom orbital modulate the spin states of the center Au atom.This kind of single atom junction contains an unique spin storage feature,which makes it a good candidate to build quantum logical circuit.The DFT investigation of H₂ O,CO₂and H₂CO₃ loading on Pt nanoparticle,indicates that the absorption effect enhances the ionization properties of H₂ O molecule and enlarges the reduction probability of distal oxygen atom in CO₂ molecule.The reaction mechanism of photoexcited electron and hole suggests a new way to improve the efficiency of photocatalytic reaction.