| Silicon-based integrated circuits has brought great changes to theworld in the last century, at the same time the miniaturization ofelectronic devices makes the conventional electronic devices areincreasingly affected by quantum effects as well as some otherfactors. With the electronic devices and equipment getting smaller,molecule-based devices research attracts more and more extensiveattention. Molecule wires with various merits such as smaller size,adjustable performance and diversity and so on are endowed with lotsof potential applications, which make counties around the worldattach great importance to the development and application of suchproducts. Although researches on molecular wires already has madesome significant progress, there is still a long way to go for realizingthe stable and reliable molecular computers because the presentstudy is still linger on the principle research of molecular wires, andthere are a lot of experiments and practical researches relating to thereliability, reproducibility and cost which need to be done. We are stilllack of the comprehensive understandings of some basic problemssuch as molecular wire behaviors in the device, the electron transfermechanism of molecular electronic devices and something like that.Therefore, the paper by using DAPDI as the molecular wires is hopefully to reveal the present researches on molecular wires and theauthor also tries to use density functional theory study in quantumchemical calculations to show changes in the behavior of themolecule under the effect of external electric field at the same timedescribe the geometric configuration of the molecule and othercharacteristics of the electronic structure changes under the effectof the external electric field which are expected to provide supportand reference to the experimental research and design of molecularwires in the future.In the first part, present researches in molecular electronics andmolecular wire will be briefly introduced. In this paper the materialsof molecular wires which are the material basis of molecular wiretechnology are conjugated polymers. Molecular wires refer to theelectroactive polymer related to the π electronic structure (linearpolylefine, polyaromatic and heteroaromatic), whose properties arerelevant to delocalized electrons. Therefore, it is also nameddeloca1ized electron polymers or conjugated polymers.In the second section, the following aspects will be presented indetail. In quantum chemistry analysis, with the rapid updating andimprovement in computer technology and theory, it becomes quiteeasy to calculate the various properties of small molecule system.This author is going to describe the theoretical calculation methodsused in this paper named density functional theory, including its basicprinciples and common methods as well as some commonly usedsoftware packages based on density functional theory. Besides, someother theoretical means and methods used in text analysis are brieflyintroduced in this part. In the third section, taking the density functional theory (DFT) as atheoretical guidance, the paper is going to do a research on amolecular wire: using Au substituting diamine N, N’-bis(4-amino-2,3,5,6-tetramethylphenyl) phtalene-1,2,4,5-dicarboximide (DAPDI), theauthor will analyze its structures and properties in different intensityof electric field with the quantum chemical calculation method. Theresearch turns out this molecular wire both its geometrical andelectronic structures are very sensitive to the external electric fieldand it also shows that the general dipole moment and the X-directioncomponent would linearly increases according to the externalelectric field, therefore this molecules can be highly polarized by astrong external field. |
PDF Full Text Request