Effects of boundary conditions on the electron structure in conducting polymers
Lu, K; Tong, GP; Yang, H; Yang, JR; Zhang, LX; Zhao, DL
AbstractAs the real trans-polyacetylene molecule has finite chain length, its chain-terminal effects on various properties should be taken into account, that is to say, the aperiodic boundary condition should be employed in studying the properties of conducting polymers. However, if trans-polyacetylene chain is long enough, the chain-terminal effects can be ignored. In this paper, a one-dimensional finite compound lattice model of trans-polyacetylene chain is adopted. With considering the chain-terminal effects and the next-neighbor hopping interactions, the energy spectra and the density of states are calculated for trans-polyacetylene chains with the lattice number N from 10 to 200 under the periodic and aperiodic boundary conditions. The effects of chain length and interaction parameter on density of states and band width are also discussed. It is shown that the curves of DOS, are symmetrical when the nearest-neighbor hopping is merely considered, and the valence and conduction bands are unsymmetrical when the next-neighbor term is taken into account. At the same time, some results under two kinds of boundary conditions are compared. When N < 50, the surface states appear under the aperiodic boundary condition, as well as DOS nearby the Feimi surface is larger than that under the periodic boundary condition. When N greater than or equal to 50, the surface states are difficult to distinguish between the valence and conduction bands, and DOS tends to be identical under two kinds of boundary conditions. Moreover, with N increasing, the difference of ionization energy under the two boundary conditions is reduced for the same parameter. In conclusion, when N < 50, there is a large difference for nearest-neighbor hopping and next-neighbor hopping due to the chain-terminal affect. This indicates that the aperiodic boundary condition plays an important role in dealing with finite systems. However, when N greater than or equal to 50, since the chain-terminal effect can be neglected, the periodic boundary condition is suitable for the finite trans-polyacetylene system.
KeywordCompound Lattice Density Of States Surface States Chain-terminal Effect
Indexed BySCI
WOS IDWOS:000183620800010
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Document Type期刊论文
Corresponding AuthorLu, K
Affiliation1.Zhejiang Univ, Dept Phys, Hangzhou 310028, Peoples R China
2.Zhejiang Normal Univ, Dept Phys, Jinhua 321004, Peoples R China
3.Chinese Acad Sci, Inst Chem, Ctr Mol Sci, Polymer Phys Lab, Beijing 100080, Peoples R China
Recommended Citation
GB/T 7714
Lu, K,Tong, GP,Yang, H,et al. Effects of boundary conditions on the electron structure in conducting polymers[J]. ACTA POLYMERICA SINICA,2003(3):374-380.
APA Lu, K,Tong, GP,Yang, H,Yang, JR,Zhang, LX,&Zhao, DL.(2003).Effects of boundary conditions on the electron structure in conducting polymers.ACTA POLYMERICA SINICA(3),374-380.
MLA Lu, K,et al."Effects of boundary conditions on the electron structure in conducting polymers".ACTA POLYMERICA SINICA .3(2003):374-380.
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