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See detailExciton dissociation at donor-acceptor heterojunctions: Dynamics using the collective effective mode representation of the spin-boson model
Chenel, Aurélie; Mangaud, Etienne; Burghardt, Irène et al

in Journal of Chemical Physics (2014), 140

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See detailReorientation of the helix of the tryptophan-rich gp41W peptide from HIV-1 at interfaces
Matar, Gladys; Benichou, Emmanuel; Nasir, Mehmet Nail ULg et al

in Journal of Chemical Physics (2013), 139

The glycoprotein gp41 from the Human Immunodeficiency Virus type 1 (HIV-1) has an amino acid sequence enriched in tryptophan residues, the so-called gp41W peptide (i.e., KWASLWNWFNITNWLWYIK) and plays a ... [more ▼]

The glycoprotein gp41 from the Human Immunodeficiency Virus type 1 (HIV-1) has an amino acid sequence enriched in tryptophan residues, the so-called gp41W peptide (i.e., KWASLWNWFNITNWLWYIK) and plays a crucial role in HIV-1 host cell infection. Using the coupling of Second Harmonic Generation targeting the tryptophan residues with lateral surface tension measurements, we investigate the interaction of gp41W with a neat air/water and a lipid/water interfaces. At the air/water interface, gp41W presents a well-defined orientation and this orientation is strongly modified at the lipid/water interface, depending on the surface pressure. These results show that this strategy is well suited to monitor tryptophan containing α-helices orientation at lipid/water interfaces. [less ▲]

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See detailHot electron production and diffuse excited states in C70, C82, and Sc3N@C80 characterized by angular-resolved photoelectron spectroscopy
Johansson, J. Olof; Bohl, Elvira; Henderson, Gordon G. et al

in Journal of Chemical Physics (2013), 139

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See detailQuantum gates in hyperfine levels of ultracold alkali dimers by revisiting constrained-phase optimal control design
Jaouadi, Amine; Barrez, Etienne; Justum, Yves et al

in Journal of Chemical Physics (2013), 139

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See detailFunctionality in single-molecule devices: Model calculations and applications of the inelastic electron tunneling signal in molecular junctions
Dash, Louise K; Ness, Hervé; Verstraete, Matthieu ULg et al

in Journal of Chemical Physics (2012), 136

We analyze how functionality could be obtained within single-molecule devices by using a combination of non-equilibrium Green's functions and ab initio calculations to study the inelastic transport ... [more ▼]

We analyze how functionality could be obtained within single-molecule devices by using a combination of non-equilibrium Green's functions and ab initio calculations to study the inelastic transport properties of single-molecule junctions. First, we apply a full non-equilibrium Green's function technique to a model system with electron-vibration coupling. We show that the features in the inelastic electron tunneling spectra (IETS) of the molecular junctions are virtually independent of the nature of the molecule-lead contacts. Since the contacts are not easily reproducible from one device to another, this is a very useful property. The IETS signal is much more robust versus modifications at the contacts and hence can be used to build functional nanodevices. Second, we consider a realistic model of a organic conjugated molecule. We use ab initio calculations to study how the vibronic properties of the molecule can be controlled by an external electric field which acts as a gate voltage. The control, through the gate voltage, of the vibron frequencies and (more importantly) of the electron-vibron coupling enables the construction of functionality: nonlinear amplification and/or switching is obtained from the IETS signal within a single-molecule device. [less ▲]

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See detailSlow Magnetic Relaxation and Electron Delocalization in an S = 9/2 Iron(II/III) Complex Featuring Two Crystallographically Inequivalent Iron Sites
Hazra, Susanta; Sasmal, Sujit; Fleck, Michel et al

in Journal of Chemical Physics (2011), 134

The magnetic, electronic and Mössbauer spectral properties of [Fe2L(μ-OAc)2]ClO4, 1, where L is the dianion of the tetraimino-diphenolate macrocyclic ligand, H2L, indicate that 1 is a class III mixed ... [more ▼]

The magnetic, electronic and Mössbauer spectral properties of [Fe2L(μ-OAc)2]ClO4, 1, where L is the dianion of the tetraimino-diphenolate macrocyclic ligand, H2L, indicate that 1 is a class III mixed valence iron(II/III) complex with an electron that is fully delocalized between two crystallographically inequivalent iron sites to yield a [Fe2]V cationic configuration with a St = 9/2 ground state. Fits of the dc magnetic susceptibility between 2 and 300 K and of the isofield variable-temperature magnetization of 1 yield an isotropic magnetic exchange parameter, J, of –32(2) cm–1 for an electron transfer parameter, B, of 950 cm–1, a zero-field uniaxial D9/2 parameter of –0.9(1) cm–1, and g = 1.95(5). In agreement with the presence of uniaxial magnetic anisotropy, ac susceptibility measurements reveal that 1 is a single-molecule magnet at low temperature with a single molecule magnetic effective relaxation barrier, Ueff, of 9.8 cm–1. At 5.25 K the Mössbauer spectra of 1 exhibit two spectral components, assigned to the two crystallographically inequivalent iron sites with a static effective hyperfine field; as the temperature increases from 7 to 310 K the spectra exhibit increasingly rapid relaxation of the hyperfine field on the iron-57 Larmor precession time of 5 × 10–8 s. A fit of the temperature dependence of the average effective hyperfine field yields |D9/2| = 0.9 cm–1. An Arrhenius plot of the logarithm of the relaxation frequency between 5 and 85 K yields a relaxation barrier of 17 cm–1. [less ▲]

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See detailLocal control of non-adiabatic dissociation dynamics
Bomble, Laëtitia; Chenel, Aurélie; Meier, Chris et al

in Journal of Chemical Physics (2011), 134

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See detailBeyond quantum microcanonical statistics
Fresch, Barbara ULg; Moro, Giorgio J.

in Journal of Chemical Physics (2011), 134

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See detailEmergence of Equilibrium Thermodynamic Properties in Quantum Pure States I. Theory.
Fresch, Barbara ULg; Moro, Giorgio J.

in Journal of Chemical Physics (2010), 133

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See detailEmergence of equilibrium thermodynamic properties in quantum pure states. II. Analysis of a spin model system
Fresch, Barbara ULg; Moro, Giorgio J.

in Journal of Chemical Physics (2010), 133

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See detailFirst-Principles conductance of nanoscale junctions from the polarizability of finite systems
Verstraete, Matthieu ULg; Bokes, Peter; Godby, Rex W

in Journal of Chemical Physics (2009), 130

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See detailVibrational computing: Simulation of a full adder by optimal control
Bomble, L.; Lauvergnat, D.; Remacle, Françoise ULg et al

in Journal of Chemical Physics (2008), 128(6),

Within the context of vibrational molecular quantum computing, we investigate the implementation of a full addition of two binary digits and a carry that provides the sum and the carry out. Four qubits ... [more ▼]

Within the context of vibrational molecular quantum computing, we investigate the implementation of a full addition of two binary digits and a carry that provides the sum and the carry out. Four qubits are necessary and they are encoded into four different normal vibrational modes of a molecule. We choose the bromoacetyl chloride molecule because it possesses four bright infrared active modes. The ground and first excited states of each mode form the one-qubit computational basis set. Two approaches are proposed for the realization of the full addition. In the first one, we optimize a pulse that implements directly the entire addition by a single unitary transformation. In the second one, we decompose the full addition in elementary quantum gates, following a scheme proposed by Vedral [Phys. Rev. A 54, 147 (1996)]. Four elementary quantum gates are necessary, two two-qubit CNOT gates (controlled NOT) and two three-qubit TOFFOLI gates (controlled-controlled NOT). All the logic operations consist in one-qubit flip. The logic implementation is therefore quasiclassical and the readout is based on a population analysis of the vibrational modes that does not take the phases into account. The fields are optimized by the multitarget extension of the optimal control theory involving all the transformations among the 2(4) qubit states. A single cycle of addition without considering the preparation or the measure or copy of the result can be carried out in a very competitive time, on a picosecond time scale. (C) 2008 American Institute of Physics. [less ▲]

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See detailComputational investigation and experimental considerations for the classical implementation of a full adder on SO2 by optical pump-probe schemes
Bomble, L.; Lavorel, B.; Remacle, Françoise ULg et al

in Journal of Chemical Physics (2008), 128(19),

Following the scheme recently proposed by Remacle and Levine [Phys. Rev. A 73, 033820 (2006)], we investigate the concrete implementation of a classical full adder on two electronic states ((X) over tilde ... [more ▼]

Following the scheme recently proposed by Remacle and Levine [Phys. Rev. A 73, 033820 (2006)], we investigate the concrete implementation of a classical full adder on two electronic states ((X) over tilde (1)A(1) and (C) over tilde B-1(2)) of the SO2 molecule by optical pump-probe laser pulses using intuitive and counterintuitive (stimulated Raman adiabatic passage) excitation schemes. The resources needed for providing the inputs and reading out are discussed, as well as the conditions for achieving robustness in both the intuitive and counterintuitive pump-dump sequences. The fidelity of the scheme is analyzed with respect to experimental noise and two kinds of perturbations: The coupling to the neighboring rovibrational states and a finite rotational temperature that leads to a mixture for the initial state. It is shown that the logic processing of a full addition cycle can be realistically experimentally implemented on a picosecond time scale while the readout takes a few nanoseconds. (c) 2008 American Institute of Physics. [less ▲]

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See detailOptimal control simulation of the Deutsch-Josza algorithm in a two-dimensional double well coupled to an environment
Ndong, Mamadou; Lauvergnat, David; Chapuisat, Xavier et al

in Journal of Chemical Physics (2007), 126

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See detailThe gold-ammonia bonding patterns of neutral and charged complexes Au m 0+/-1-(NH3)n. I. Bonding and charge alternation.
Kryachko, Eugène ULg; Remacle, Françoise ULg

in Journal of Chemical Physics (2007), 127(19), 194305

The gold-ammonia bonding patterns of the complexes which are formed between the ammonia clusters (NH/sub 3/)/sub 1<or=n<or=3/ and gold clusters of different sizes that range from one gold atom to the tri ... [more ▼]

The gold-ammonia bonding patterns of the complexes which are formed between the ammonia clusters (NH/sub 3/)/sub 1<or=n<or=3/ and gold clusters of different sizes that range from one gold atom to the tri-, tetra-, and 20-nanogold clusters are governed by two basic and fundamentally different ingredients: the anchoring Au-N bond and the nonconventional N-H ... Au hydrogen bond. The latter resembles, by all features, a conventional hydrogen bond and is formed between a typical conventional proton donor N-H group and the gold cluster that behaves as a nonconventional proton acceptor. We provide strong computational evidence that the gold-ammonia bonding patterns exhibit distinct characteristics as the Z charge state of the gold cluster varies within Z=0,+/-1. The analysis of these bonding patterns and their effects on the N-H ... N H-bonded ammonia clusters are the subject of this paper. [less ▲]

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See detailThe time scale for electronic reorganization upon sudden ionization of the water and water-methanol hydrogen bonded dimers and of the weakly bound NO dimer
Remacle, Françoise ULg; Levine, R. D.

in Journal of Chemical Physics (2006), 125(13),

When the valence molecular orbital is localized sudden ionization can cause the nascent hole to move rapidly even before any relaxation of the geometry occurs. Hydrogen bonded clusters offer suitable test ... [more ▼]

When the valence molecular orbital is localized sudden ionization can cause the nascent hole to move rapidly even before any relaxation of the geometry occurs. Hydrogen bonded clusters offer suitable test systems where the hole is initially localized on one moiety. Computational studies are reported for the water dimer and water-methanol bimer. The local ionization potential of water is different in the methanol-water and water-methanol conformers and this difference is very clearly reflected in the dynamics of charge migration. For the NO dimer the results are that its structure is symmetric so that the two NO molecules are equivalent and do not exhibit the required localization. The role of symmetry is also evident in the charge propagation for holes created in different orbitals. Localization of the initial hole distribution even if absent in the bare molecule can still be induced by the intense electric field of a sudden photoionization. This effect is computationally studied for the NO dimer in the presence of a static electric field. (c) 2006 American Institute of Physics. [less ▲]

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See detailWave packets in a bifurcating region of an energy landscape: Diels-Alder dimerization of cyclopentadiene
Lasorne, Benjamin; Dive, Georges ULg; Desouter, Michèle ULg

in Journal of Chemical Physics (2005), 122(18), 1843041-10

Quantum dynamics in a valley ridge inflection (VRI) point region is analyzed in the case of the Diels-Alder endo-dimerization of cyclopentadiene pointed out recently by [Caramella , J. Am. Chem. Soc. 124 ... [more ▼]

Quantum dynamics in a valley ridge inflection (VRI) point region is analyzed in the case of the Diels-Alder endo-dimerization of cyclopentadiene pointed out recently by [Caramella , J. Am. Chem. Soc. 124, 1130 (2002)]. The VRI point is located along the reaction path connecting the bispericyclic symmetrical transition structure put in evidence by Caramella and the transition state of the Cope rearrangement. Dynamics is carried out by using constrained Hamiltonian methodology. The active coordinates are the first formed C-C bond length and the difference between the two other C-C bond lengths which achieve the dimerization as 4+2 or 2+4 adducts. A two-dimensional (2D) minimum-energy surface have been computed at the Becke 3 Lee-Yong-Parr/6-31G(*) level. The energy landscape can be classified as an uphill ridge-pitchfork VRI bifurcation according to a recent classification of bifurcation events [W. Quapp, J. Mol. Struct. 695-696, 95 (2004)]. Dynamics does not describe the thermal reaction but concerns wave packets which could be prepared by pulse reagents, i.e., by coherent control. We analyze how the shape and initial location on the ground potential-energy surface are linked to the synchronous or asynchronous mechanism of the final step after the first transition state. We use a one-dimensional model of optimum control theory to check the feasibility of such a coherent preparation. The wave-packet evolution in the VRI domain is well explained by semiclassical predictions even with the negative curvature of the unstable ridge. Finally, a crude model of dissipation has been introduced to test the stability of the 2D predictions. (c) 2005 American Institute of Physics. [less ▲]

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See detailRole of angular momentum conservation in unimolecular translational energy release: Validity of the orbiting transition state theory
Gridelet, Evelyne; Lorquet, Jean-Claude ULg; Leyh, Bernard ULg

in Journal of Chemical Physics (2005), 122(9), 94106

The translational kinetic energy release distribution (KERD) for the halogen loss reaction of the bromobenzene and iodobenzene cations has been reinvestigated on the microsecond time scale. Two necessary ... [more ▼]

The translational kinetic energy release distribution (KERD) for the halogen loss reaction of the bromobenzene and iodobenzene cations has been reinvestigated on the microsecond time scale. Two necessary conditions of validity of the orbiting transition state theory (OTST) for the calculation of kinetic energy release distributions (KERDs) have been formulated. One of them examines the central ion-induced dipole potential approximation. As a second criterion, an adiabatic parameter is derived. The lower the released translational energy and the total angular momentum, the larger the reduced mass, the rotational constant of the molecular fragment, and the polarizability of the released atom, the more valid is the OTST. Only the low-energy dissociation of the iodobenzene ion (E approximately 0.45 eV, where E is the internal energy above the reaction threshold) is found to fulfill the criteria of validity of the OTST. The constraints that act on the dissociation dynamics have been studied by the maximum entropy method. Calculations of entropy deficiencies (which measure the deviation from a microcanonical distribution) show that the pair of fragments does not sample the whole of the phase space that is compatible with the mere specification of the internal energy. The major constraint that results from conservation of angular momentum is related to a reduction of the dimensionality of the dynamics of the translational motion to a two-dimensional space. A second and minor constraint that affects the KERD leads to a suppression of small translational releases, i.e., accounts for threshold behavior. At high internal energies, the effects of curvature of the reaction path and of angular momentum conservation are intricately intermeddled and it is not possible to specify the share of each effect. [less ▲]

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See detailNon-adiabatic interactions in wave packet dynamics of the bromoacetyl chloride photodissociation
Lasorne, Benjamin; Bacchus-Montabonel, Marie-Christine; Vaeck, Nathalie et al

in Journal of Chemical Physics (2004), 120(3), 1271-1278

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See detailCumulative isomerization probability by various transition state wave packet methods including the MCTDH algorithm
Lasorne, Benjamin; Gatti, Fabien; Baloïtcha, Ezinvy et al

in Journal of Chemical Physics (2004), 121

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