Abstract: We present the exact numerical diagonalization of the Mulliken donor-acceptor (DA) dimer with Holstein coupling. The resulting eigenstates are introduced in sum-over-states expressions of static optical susceptibilities. The careful partitioning of the sum, and the comparison with spectral properties give important clues on the role of electron-phonon (e-ph) coupling. Anharmonicity does not appreciably affect vibrational spectra. nor linear electronic spectra, and is irrelevant for the static linear polarizability. By contrast, huge anharmonic contributions to hyperpolarizabilities are found: the harmonic approximation is unreliable for the calculation of non-linear responses, even for systems where it hardly affects linear optical spectra. (C) 2001 Elsevier Science B.V. All rights reserved.
Anharmonicity and NLO responses: an exact diagonalization study / DEL FREO, Luca; Painelli, Anna. - In: CHEMICAL PHYSICS LETTERS. - ISSN 0009-2614. - 338:(2001), pp. 208-216.
Anharmonicity and NLO responses: an exact diagonalization study
DEL FREO, Luca;PAINELLI, Anna
2001-01-01
Abstract
Abstract: We present the exact numerical diagonalization of the Mulliken donor-acceptor (DA) dimer with Holstein coupling. The resulting eigenstates are introduced in sum-over-states expressions of static optical susceptibilities. The careful partitioning of the sum, and the comparison with spectral properties give important clues on the role of electron-phonon (e-ph) coupling. Anharmonicity does not appreciably affect vibrational spectra. nor linear electronic spectra, and is irrelevant for the static linear polarizability. By contrast, huge anharmonic contributions to hyperpolarizabilities are found: the harmonic approximation is unreliable for the calculation of non-linear responses, even for systems where it hardly affects linear optical spectra. (C) 2001 Elsevier Science B.V. All rights reserved.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.