Lattice Dynamics of Molecular Crystals

Califano, S.; Schettino, Vincenzo; Neto, N.

doi:10.1007/978-3-642-93186-4

Cited by 203 publications

(194 citation statements)

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“…For this purpose we adopt an exciton-like model. 29 To start with, it is convenient to use a set of molecular coordinates Q i describing translations, rotations and internal vibrations of the molecular units in the crystal. To each BEDT-TTF molecule of N = 26 atoms we associate the following 3N coordinates: 3 mass-weighted cartesian displacements of the center of mass, 3 inertia-weighted rotations about the principal axes of inertia, and 3N − 6 = 72 internal vibrations (the normal modes of the isolated BEDT-TTF molecule).…”

Section: Coupling With Low-frequency Intra-molecular Degrees Of Frmentioning

confidence: 99%

Lattice dynamics and electron-phonon coupling in theβ−(BEDT−TTF)2I3
Girlando
¹
,
Masino
²
,
Visentini
³

et al. 2000
Phys. Rev. B
35
1
38
0
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The crystal structure and lattice phonons of (BEDT-TTF)2I3 superconducting β-phase (where BEDT-TTF is bis-ethylen-dithio-tetrathiafulvalene) are computed and analyzed by the Quasi Harmonic Lattice Dynamics (QHLD) method. The empirical atom-atom potential is that successfully employed for neutral BEDT-TTF and for non superconducting α-(BEDT-TTF)2I3. Whereas the crystal structure and its temperature and pressure dependence are properly reproduced within a rigid molecule approximation, this has to be removed account for the specific heat data. Such a mixing between lattice and low-frequency intra-molecular vibrations also yields good agreement with the observed Raman and infrared frequencies. From the eigenvectors of the low-frequency phonons we calculate the electron-phonon coupling constants due to the modulation of charge transfer (hopping) integrals. The charge transfer integrals are evaluated by the extended Hückel method applied to all nearest-neighbor BEDT-TTF pairs in the ab crystal plane. From the averaged electron-phonon coupling constants and the QHLD phonon density of states we derive the Eliashberg coupling function α(ω)F (ω), which compares well with that experimentally obtained from point contact spectroscopy. The corresponding dimensionless coupling constant λ is found to be ∼ 0.4. 74.70. Kn,74.25.Kc

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Section: Coupling With Low-frequency Intra-molecular Degrees Of Frmentioning

confidence: 99%

Lattice dynamics and electron-phonon coupling in theβ−(BEDT−TTF)2I3
Girlando
¹
,
Masino
²
,
Visentini
³

et al. 2000
Phys. Rev. B
35
1
38
0
View full text Add to dashboard Cite

show abstract

“…2D IR techniques are femtosecond optical analogues of 2D NMR that generate 2D correlation plots that can separate homogeneous and inhomogeneous broadenings along the diagonal and antidiagonal axis and provide a rich cross-peak pattern (21). Electrostatic interactions strongly contribute to the optical response of molecular crystals (22), polypeptides (23,24), and neat liquids (25). In a previous study the Coulomb coupling between sn-1 and sn-2 carbonyls in a phospholipid molecule was considered negligible (8).…”

mentioning

confidence: 99%

Electrostatic interactions in phospholipid membranes revealed by coherent 2D IR spectroscopy

Volkov¹,

Chelli

Zhuang

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

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The inter-and intramolecular interactions of the carbonyl moieties at the polar interface of a phospholipid membrane are probed by using nonlinear femtosecond infrared spectroscopy. Twodimensional IR correlation spectra separate homogeneous and inhomogeneous broadenings and show a distinct cross-peak pattern controlled by electrostatic interactions. The inter-and intramolecular electrostatic interactions determine the inhomogeneous character of the optical response. Using molecular dynamics simulation and the nonlinear exciton equations approach, we extract from the spectra short-range structural correlations between carbonyls at the interface.carbonyl ͉ interface ͉ intermolecular ͉ nonlinear exciton equations ͉ molecular dynamics A s a constituent organelle in a cell, the membrane sets the information and energy gradients necessary for life. Carbonyl, phosphate, and choline are the common structural moieties in the polar surface of cellular membranes (1), mediating molecular recognition and signal transduction (1-4). Unfortunately, our knowledge on their arrangement and dynamics is rather limited due to experimental difficulties. In a lipid bilayer, lateral irregularity smears the diffraction pattern in neutron scattering measurements, and NMR resonances are broad because of the restricted motions that result in incomplete motional narrowing. IR spectroscopy, on the other hand, is known to be helpful in application to such systems. Since 1972, the IR resonance of carbonyl moieties in phospholipid membranes has attracted considerable attention (5-9). The absorption band shows a clear inhomogeneous character and can be described as a superposition of several substates (5-7). The carbonyl stretching line-shapes in membranes could yield direct information about molecular architecture and fluctuations in the membrane interface (10, 11), provided that the origin of the spectral inhomogeneity of the carbonyl IR response in phospholipid membranes is understood. The inhomogeneity was attributed to differences in the local environment of the sn-1 and sn-2 carbonyl moieties stemming from the packing arrangements (6, 8), the local chain conformations (8,9,(12)(13)(14), the relative positions of the two CAO groups with respect to the interface (9, 15), and the degree of hydration (16,17). In an elegant work, Blume et al. (16) ruled out all of the scenarios involving local structural differences except hydrogen bonding. In a recent study, we eliminated the variance in hydration as a possible source of inhomogeneity (18).Here we employ 2D IR spectroscopy (19,20) to explore whether and to what extent the inhomogeneities of the carbonyl absorption can be attributed to electric field fluctuations. 2D IR techniques are femtosecond optical analogues of 2D NMR that generate 2D correlation plots that can separate homogeneous and inhomogeneous broadenings along the diagonal and antidiagonal axis and provide a rich cross-peak pattern (21). Electrostatic interactions strongly contribute to the optical response of molecular crystals (2...

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“…Because of the smallness of the area, the width of the ring surface should be large enough to avoid possible errors caused by the pointing process (say, a ring surface width of between 1 and 5 cm); -to measure the effect of small accelerations on test particles, the surface of the ring could consist of a homogeneous crystal lattice of known molecular structure, and mechanical and electronic properties. The characteristics of the crystal, such as the particle diameter, lattice and dielectric constant, Curie temperature, conductance and the lattice exact phonon mode frequencies could be used for the baseline calibration of the crystal lattice (for lattice dynamics theory see Born & Huang 1954;Walmsley 1975;and Califano et al 1981). In this case, the detection of the small acceleration regime could be achieved statistically by comparing the calibration laboratory spectral pattern (a control template) with the experimental spectral pattern of the frequencies from the reloaded experimental data.…”

Section: Final Remarksmentioning

confidence: 99%

Testing the Newton second law in the regime of small accelerations

Lorenci

Faúndez-Abans²,

Pereira

2009

A&A

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It has been pointed out that the Newtonian second law can be tested in the very small acceleration regime by using the combined movement of the Earth and Sun around the Galactic center of mass. It has been shown that there are only two brief intervals during the year in which the experiment can be completed, which correspond to only two specific spots on the Earth surface. An alternative experimental setup is presented to allow the measurement to be made on Earth at any location and at any time.

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Lattice Dynamics of Molecular Crystals

Cited by 203 publications

References 0 publications

Lattice dynamics and electron-phonon coupling in theβ−(BEDT−TTF)2I3
Girlando
¹
,
Masino
²
,
Visentini
³

et al. 2000
Phys. Rev. B
35
1
38
0
View full text Add to dashboard Cite

Lattice dynamics and electron-phonon coupling in theβ−(BEDT−TTF)2I3
Girlando
¹
,
Masino
²
,
Visentini
³

et al. 2000
Phys. Rev. B
35
1
38
0
View full text Add to dashboard Cite

Electrostatic interactions in phospholipid membranes revealed by coherent 2D IR spectroscopy

Testing the Newton second law in the regime of small accelerations

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Lattice Dynamics of Molecular Crystals

Cited by 203 publications

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Lattice dynamics and electron-phonon coupling in theβ−(BEDT−TTF)2I3Girlando1, Masino2, Visentini3 et al. 2000Phys. Rev. B351380View full textAdd to dashboardCite

Lattice dynamics and electron-phonon coupling in theβ−(BEDT−TTF)2I3Girlando1, Masino2, Visentini3 et al. 2000Phys. Rev. B351380View full textAdd to dashboardCite

Electrostatic interactions in phospholipid membranes revealed by coherent 2D IR spectroscopy

Testing the Newton second law in the regime of small accelerations

Contact Info

Product

Resources

About

Lattice dynamics and electron-phonon coupling in theβ−(BEDT−TTF)2I3
Girlando
¹
,
Masino
²
,
Visentini
³

et al. 2000
Phys. Rev. B
35
1
38
0
View full text Add to dashboard Cite

Lattice dynamics and electron-phonon coupling in theβ−(BEDT−TTF)2I3
Girlando
¹
,
Masino
²
,
Visentini
³

et al. 2000
Phys. Rev. B
35
1
38
0
View full text Add to dashboard Cite