1988 Fiscal Year Final Research Report Summary
Properties and Control of Solitons
| Project/Area Number |
61540261
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
物性一般（含極低温･固体物性に対する理論）
|
|---|
| Research Institution | University of Tokyo |
|---|
Principal Investigator |
WADA Yasushi Faculty of Science, University of Tokyo, 理学部, 教授 (70011476)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
ONO Yoshiyuki Faculty of Science, Toho University, 理学部, 助教授 (30011761)
|
|---|
| Project Period (FY) |
1986 – 1988
|
| Keywords | Soliton / Phonon / Polaron / ^4 system / Polyacetylene / Diffusive motion / Doping / 光誘起ラマン散乱 |
|---|
| Research Abstract |
1. Soliton in the ^4-system :
Phonon transfers momentum in higher order collision processes with a soliton. It induces a diffusive motion of the soliton. Effect of the phonon quantization changes temperature dependence of friction coefficient to an activation type. The ^4-system has thus been extensively studied as a prototype for the soliton diffusion.
2. Soliton in polyacetylene :
(1) Optical phonons : Optical phonons interact strongly with electrons. Phase shift analysis shows that they transfer the momentum to the soliton in the collision process of lower order. Temperature and frequency dependences of the soliton diffusion coef-ficient are obtained. The quantum effect is dominant as in the ^4-system.
(2) Acoustic phonons : Acoustic phonons are important at low temperatures in spite of their weak interactions. Their structures are investigated analytically as well as numerically.
(3) Electron correlation : Localized phonon modes around a soliton or polaron do survive the electron correlation as far as it is taken into account in the Hartree-Fock approximation. We find the approximation overestimates effects of the corre-lation.
3. Polyacetylene and doping :
Doping is simulated by an electron-phonon system with random distribution of impurities. It is studied numerically and analytically. We find the soliton creation and pinning, optical activation of localized phonons, new types of solitons and informations on the impurity bands. This discussion can be applied to phase transition of a soliton lattice.
4. Photoinduced Raman scattering :
Photoinduced absorption is found to be not effective in distinguishing soliton from polaron. We suggest that the Raman process should be useful.
5. Fractionally charged solitons :
It is not succeeded to obtain analytical solutions for the solitons. Numerical analyses are extensively performed to get informations of structures of various solitons. They would give helpful guidelines for future works.
|
