Effect Of Electron-lattice Interaction On Electronic Transpotr Propetries In Conjugated Polymers

In recent years, with the miniaturization of devices and integration gradually improve,raised a hot wave people study of molecular devices. Molecular devices using organicmolecular monolayer or a single molecules as a medium to control photoelectric signal, thecharge transport in the device is the most basic physical processes. There are many theories tostudy the electron transport properties of molecular devices.Green’s function method is used for many in the study of the physical system, and madea great success, many physical properties can be explained by green’s function. However,with the progress of science and technology the new physical phenomena were observed,these phenomena involved in the system a lot are the interaction of multibody system, and weare using the green’s function to handle these problems usually need to deal with the problemby perturbation approximation, and we cannot explain these phenomena by perturbationapproximation, so we use the theory of scattering to deal with these problems.This paper first introduces the Hershfield scattering theory, illustrates we can constructan effective Hamiltonian, integration the infinite library into the effective Hamiltonian, thiswill use the scattering operator, we use SSH model in the middle of the chain, through theLippman-Schwinger equation we can get corresponding equations, then calculate the latticeconfiguration polyacetylene. This paper calculated the nondegenerate ground state of thepolymer chain lattice model and its current under different bias, compares the differencebetween degenerate and nondegenerate states of polyacetylene. The band gap of degeneratestate of polyacetylene chain is smaller,and the band gap of polyacetylene chain ofnondegenerate states is larger. The soliton-antisoliton pair can be formed in degenerate state,not in nondegenerate state. This is because there have different phase in degenerate state. Ifthere have A phase and B phase, polyacetylene chain is in A phase at the begin, then there is asmall excitation. It will make the lattice in A phase become B phase in a part of the chain, Itwill become soliton in the intersection of A phase and B phase. If the soliton-antisoliton pairhappen when B phase in the middle of A phase. There will form multiple soliton-antisolitonpair if the chain is long enough. For nodegenerate state polyacetylene chains, It will not formsoliton-antisoliton pair because the energy is different betweet the ground state and other state.At the same time, this article studied the transport properties of quantum ring. Due toquantum ring can be used to realize the interference of spin, and Aharonov-Bohm effect canbe observed in quantum ring. The quantum ring can be divided into two categories: one kindis circular quantum ring; Another kind is a polygon quantum ring. This paper is to studytransport properties of quantum ring round, The beginning is the simplification ofHamiltonian, Because the quantum ring is two-dimensional, So the Hamiltonian istwo-dimensional. We can simplify the Hamiltonian for one dimension, we can calculated theeigen states and eigen energy of the system by one dimensional Hamiltonian. Then calculatethe conductance through the landau formula. In this paper we calculate the conductance withmethod of matrix, and made a comparison withG NMT.