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  • 1
    Electronic Resource
    Electronic Resource
    Exotic exciton–phonon states and bottleneck for self-trapping (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 4003-4011 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In a previous paper the conventional barrier model of excitonic self-trapping has been shown to display divergencies. In the present work we report on novel "exotic'' exciton–phonon states, which have not been noted so far. These states are of non-self-trapping nature, and by way of their small extension in Q space they may acquire a "bottleneck'' role in the process of energy dissipation. This seems to allow for a new explanation of the fast luminescence found in rare gas and other crystals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.457814
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  • 2
    Electronic Resource
    Electronic Resource
    A Fulton–Gouterman approach to exciton localization and excitonic solitons (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 3036-3044 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A one dimensional model for Frenkel excitons interacting with acoustical phonons is considered. The generalized Fulton–Gouterman transcription lays open a peculiar topological property which is very suggestive for variational calculations. A very simple Ansatz is shown to yield already lower groundstate energies than previous dressed exciton or soliton theories, containing both latter as special limits.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.456925
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  • 3
    Electronic Resource
    Electronic Resource
    Solitonic Bloch functions and others in the Fulton–Gouterman frame of exciton-phonon systems (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 97 (1992), S. 5037-5047 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A one-dimensional model for Frenkel excitons interacting with acoustical phonons is considered. The generalized Fulton–Gouterman (FG) transcription reduces the problem to a pure vibrational one and simultaneously guarantees the Bloch nature of any exciton-phonon eigenfunction. A general variational ansatz is established with regard to the specific topological structure of the FG equations. Simplified versions of this ansatz are shown to yield lower ground-state energies than any previously used dressed exciton or localized solitonic ("non-Blochian'') trial functions for all coupling-transfer regimes. This evinces the practicability of the FG conception also in extremal coupling-transfer situations. Since the calculation is easily extended to excited states, the FG approach seems to be an adequate means to investigate energy transport in exciton-phonon systems. In particular, the solitonic problem in these systems may be analyzed on a discrete footing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.463858
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  • 4
    Electronic Resource
    Electronic Resource
    On the contrast between the Lee–Low–Pines and the generalized Fulton–Gouterman transformation (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 5675-5685 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In this work we compare the generalized Fulton–Gouterman transformation (GFGT) and the Lee–Low–Pines transformation (LLPT). We apply both to a general electron-phonon Hamiltonian including the Fröhlich Hamiltonian, an electronic periodic potential, phononic anharmonicities, and Umklapp processes. We respectively discuss the ability of the two unitary transformations to achieve approximate electronic diagonalization in general and also for a particular electronic Bloch base. We further consider their possible application to multiparticle systems. It turns out that in general the GFGT is a more successful technique than the LLPT. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1290034
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  • 5
    Electronic Resource
    Electronic Resource
    Nonadiabatic divergence in barrier models of excitonic self-trapping (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 7550-7558 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The conventional adiabatic concept for excitonic self-trapping via local lattice relaxation is shown to display a fundamental divergence if the oscillatory kinetic energy operator is consistently accounted for. This outcome is due to an extreme violation of the adiabatic principle. Consequently, the often used "barrier models'' of self-trapping lose their theoretical justification. Possible alternative concepts for "delayed'' self-trapping are shortly indicated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.454319
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  • 6
    Electronic Resource
    Electronic Resource
    A method of moments for the optical Jahn-Teller problem (1970)
    Springer
    The European physical journal 230 (1970), S. 460-480 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A Method of moments is presented for optical transitions to Jahn-Teller states. The Condon and a modified Born-Oppenheimer approximation have been adopted. On the basis of these 2 principles, the method is exact. Specific orthonormality and closure properties are derived for Jahn-Teller states, which are essential for performing the calculation. As illustrative examples the pure Jahn-Teller casesE-e andT-t have been calculated in the strong coupling limit. Each of these cases leads to specific combinatorial problems and to an application of Wick's theorem. The latter is common to both cases. Comparison with the semi-classical calculation reveals the identity of the results for theE- e system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01394491
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  • 7
    Electronic Resource
    Electronic Resource
    Quasi-exact solution of the optical Jahn-Teller problem (1971)
    Springer
    The European physical journal 244 (1971), S. 275-288 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The presented method is based on an extension of the Goldberger-Adams theorem and on a systematic application of Wick's theorem. The latter leads to combinatorial problems, which in general are complicated but well-fit to be handled by computers. In the two pureJT-casesE-e andT-t the combinatorial problems are simple. In particular in theE-e-case (trigonal) the optical response can be written in a concise analytical form. It is shown further that by means of a one-to-one correspondence of the respective combinatorial problems it suffices to calculate the complete sequence of moments in the strong coupling limit to write down expressions for the optical response with arbitrary coupling, which are exact both in the strong and weak coupling limit.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01395572
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  • 8
    Electronic Resource
    Electronic Resource
    Dispersion dynamics of crystal lattices (1967)
    Springer
    The European physical journal 206 (1967), S. 131-149 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A new formalism is presented, which has not the difficulties of the conventionalGreen's function methods for disturbed lattice dynamics. The new method introduces aGreen's function and an eigenvector-function, which are defined in the wholeω-plane. A simple device allows to extract the conventional eigenvectors and eigenfrequencies from the eigenvector-function. AGreen's function formalism and a random-phase assumption make it possible to calculate the disturbed eigenvector-function from the undisturbed one in such a way that both are normalized to the respective density of frequencies. The formalism thus is well-fit to describe changes of the density of frequencies, shifts of the bands and discrete (localized) solutions outside the bands. Applicability to the elastic continuum and quantum mechanics seem also possible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01325922
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  • 9
    Electronic Resource
    Electronic Resource
    Vibrational analysis of the sideband of theU-center local mode absorption (1967)
    Springer
    The European physical journal 207 (1967), S. 111-118 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A more general coupling of the central ion to its nearest neighbours, than that used so far, is established. Group theoretical argumentation reveals the free choice of 3 parameters instead of one. This especially includes a coupling toT 2g modes, from which it is shown that it is by no means negligible. In this way the agreement to the experimental result can be improved considerably, and an asignment of the peaks in the sideband to the different species of modes is possible. Numerical results are given for KBr.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01326221
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  • 10
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    Sobre algunas palabras gitano-españolas y otras jergales (1941)
    Madrid : Periodicals Archive Online (PAO)
    Revista de filología española. 25 (1941) 161-181 
    Details
    ISSN: 0210-9174
    Topics: Romance Studies
    URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pao:&rft_dat=xri:pao:article:4173-1941-025-00-000009
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