Quantum Theory of a Two-Dimensional Rotator in a Dissipative Environment: Application to Far-Infrared Spectroscopy.
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- Suzuki Yoko
- Institute for Molecular Science Myodaiji, Okazaki 444-8585
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- Tanimura Yoshitaka
- Institute for Molecular Science Myodaiji, Okazaki 444-8585
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Abstract
Quantum coherence and its destruction by coupling to a dissipative environment play important roles in time-resolved optical response. We study a two-time correlation function of a two-dimensional rotator coupled to a harmonic-oscillator bath. Generating functionals of reduced density matrix elements for the rotator degrees of freedom are calculated by diagonalizing the total Hamiltonian with the use of unitary transformations and then performing path integrals. A closed-form expression of linear absorption spectrum for a dipole rotator, i.e., a Fourier transformation of the dipole two-time correlation function, is derived from the generating functionals characterized by the bath spectral density. Based on the theory, the spectra for a methyl rotation in a toluene are depicted for various damping constants and temperatures. Because of the cyclic boundary condition that is constrained to fit the rotator degree of freedom, the energy states of the rotator in the absence of damping are discrete: the spectra consist of rotational branches, which correspond to change of the angular momentum. Owing to damping, the spectra exhibit a continuous band which is broadened as temperatures increase.
Journal
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- Journal of the Physical Society of Japan
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Journal of the Physical Society of Japan 70 (5), 1167-1170, 2001
THE PHYSICAL SOCIETY OF JAPAN
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Details 詳細情報について
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- CRID
- 1390282679159762560
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- NII Article ID
- 210000103021
- 110001971965
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- NII Book ID
- AA00704814
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- BIBCODE
- 2001JPSJ...70.1167S
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- ISSN
- 13474073
- 00319015
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- NDL BIB ID
- 5788477
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- Text Lang
- en
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- Data Source
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- JaLC
- NDL
- Crossref
- CiNii Articles
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- Abstract License Flag
- Disallowed