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Potential Energy And Dipole Moment Surfaces Of H-3(-) Molecule, M. Ayouz, R. Guérout, J. Robert, V. Kokoouline
Potential Energy And Dipole Moment Surfaces Of H-3(-) Molecule, M. Ayouz, R. Guérout, J. Robert, V. Kokoouline
Faculty Bibliography 2010s
A new potential energy surface for the electronic ground state of the simplest triatomic anion H-3(-) is determined for a large number of geometries. Its accuracy is improved at short and large distances compared to previous studies. The permanent dipole moment surface of the state is also computed for the first time. Nine vibrational levels of H-3(-) and 14 levels of D-3(-) are obtained, bound by at most similar to 70 and similar to 126 cm(-1), respectively. These results should guide the spectroscopic search of the H-3(-) ion in cold gases (below 100K) of molecular hydrogen in the presence of …
Weak Antiferromagnetic Coupling In Molecular Ring Is Predicted Correctly By Density Functional Theory Plus Hubbard U, Shruba Gangopadhyay, Artëm E. Masunov, Eliza Poalelungi, Michael N. Leuenberger
Weak Antiferromagnetic Coupling In Molecular Ring Is Predicted Correctly By Density Functional Theory Plus Hubbard U, Shruba Gangopadhyay, Artëm E. Masunov, Eliza Poalelungi, Michael N. Leuenberger
Faculty Bibliography 2010s
We apply density functional theory with empirical Hubbard U parameter (DFT+U) to study Mn-based molecular magnets. Unlike most previous DFT+U studies, we calibrate U parameters for both metal and ligand atoms using five binuclear manganese complexes as the benchmarks. We note delocalization of the spin density onto acetate ligands due to pi-back bonding, inverting spin polarization of the acetate oxygen atoms relative to that predicted from superexchange mechanism. This inversion may affect the performance of the models that assume strict localization of the spins on magnetic centers for the complexes with bridging acetate ligands. Next, we apply DFT+U methodology to …
Low-Energy K-Shell Compton Scattering, E. G. Drukarev, A. I. Mikhailov, I. A. Mikhailov
Low-Energy K-Shell Compton Scattering, E. G. Drukarev, A. I. Mikhailov, I. A. Mikhailov
Faculty Bibliography 2010s
We calculate the photon energy distribution and the total cross section for the Compton scattering on the K electrons for the case when the photon wave length is much smaller than the size of the K shell. We show that at the energies of the order of the binding energy I of the K electron most part of the spectrum is governed by the low-energy behavior. The total cross section has a local maximum at the energies (1.5-2)I, reaching the values of the order 1 barn. At higher photon energies the spectrum curves have two maxima, corresponding to low-energy ejected …
Wave Propagation In Waveguide Arrays With Alternating Positive And Negative Couplings, Nikolaos K. Efremidis, Peng Zhang, Zhigang Chen, Demetrios N. Christodoulides, Christian E. Rüter, Detlef Kip
Wave Propagation In Waveguide Arrays With Alternating Positive And Negative Couplings, Nikolaos K. Efremidis, Peng Zhang, Zhigang Chen, Demetrios N. Christodoulides, Christian E. Rüter, Detlef Kip
Faculty Bibliography 2010s
We introduce a waveguide array model with alternating positive and negative couplings between adjacent waveguides. Two different settings where such a model can be realized are identified as arrays of defects in Bragg gratings and arrays with propagation constants that periodically vary along the propagation direction. We analyze the properties of wave propagation in such waveguide arrays and find several interesting properties that have no counterpart in the case of arrays with constant couplings. These include the beam self-splitting, self-induced Talbot oscillations, symmetric evolution of Bloch oscillations, and new families of lattice solitons.
Temperature Dependence Of Binary And Ternary Recombination Of D-3(+) Ions With Electrons, T. Kotrík, P. Dohnal, I. Korolov, R. Plašil, Š. Roučka, J. Glosík, Chris H. Greene, V. Kokoouline
Temperature Dependence Of Binary And Ternary Recombination Of D-3(+) Ions With Electrons, T. Kotrík, P. Dohnal, I. Korolov, R. Plašil, Š. Roučka, J. Glosík, Chris H. Greene, V. Kokoouline
Faculty Bibliography 2010s
Flowing and stationary afterglow experiments were performed to study the recombination of D-3(+) ions with electrons at temperatures from 77 to 300 K. A linear dependence of apparent (effective) binary recombination rate coefficients on the pressure of the helium buffer gas was observed. Binary (D-3(+)+e(-)) and ternary (D-3(+)+e(-)+He) recombination rate coefficients were derived. The obtained binary rate coefficient agrees with recent theoretical values for dissociative recombination of D-3(+). We describe the observed ternary process by a mechanism with two rate determining steps. In the first step, a rotationally excited long-lived neutral D-3* is formed in D-3(+)-e(-) collisions. As the second …
Photoassociation Of A Cold-Atom-Molecule Pair: Long-Range Quadrupole-Quadrupole Interactions, M. Lepers, O. Dulieu, Viatcheslav Kokoouline
Photoassociation Of A Cold-Atom-Molecule Pair: Long-Range Quadrupole-Quadrupole Interactions, M. Lepers, O. Dulieu, Viatcheslav Kokoouline
Faculty Bibliography 2010s
The general formalism of the multipolar expansion of electrostatic interactions is applied to the calculation of the potential energy between an excited atom (without fine structure) and a ground-state diatomic molecule at large mutual separations. Both partners exhibit a permanent quadrupole moment so that their mutual long-range interaction is dominated by a quadrupole-quadrupole term, which is attractive enough to bind trimers. Numerical results are given for an excited Cs(6(2)P) atom and a ground-state Cs(2) molecule. The prospects for achieving photoassociation of a cold-atom-dimer pair are thus discussed and found promising. The formalism can be generalized to the long-range interaction between …
Pt-Symmetric Optical Lattices, Konstantinos G. Makris, Ramy El-Ganainy, Demetrios N. Christodoulides, Z. H. Musslimani
Pt-Symmetric Optical Lattices, Konstantinos G. Makris, Ramy El-Ganainy, Demetrios N. Christodoulides, Z. H. Musslimani
Faculty Bibliography 2010s
The basic properties of Floquet-Bloch (FB) modes in parity-time (PT)-symmetric optical lattices are examined in detail. Due to the parity-time symmetry of such complex periodic potentials, the corresponding FB modes are skewed (nonorthogonal) and nonreciprocal. The conjugate pairs of these FB modes are obtained by reflecting both the spatial coordinate and the Bloch momentum number itself. The orthogonality conditions are analytically derived for a single cell, for both a finite and an infinite lattice. Some of the peculiarities associated with the diffraction dynamics in PT lattices such as nonreciprocity, power oscillations, and phase dislocations, are also examined.
Bound On Quantum Computation Time: Quantum Error Correction In A Critical Environment, E. Novais, Eduardo R. Mucciolo, Harold U. Baranger
Bound On Quantum Computation Time: Quantum Error Correction In A Critical Environment, E. Novais, Eduardo R. Mucciolo, Harold U. Baranger
Faculty Bibliography 2010s
We obtain an upper bound on the time available for quantum computation for a given quantum computer and decohering environment with quantum error correction implemented. First, we derive an explicit quantum evolution operator for the logical qubits and show that it has the same form as that for the physical qubits but with a reduced coupling strength to the environment. Using this evolution operator, we find the trace distance between the real and ideal states of the logical qubits in two cases. For a super-Ohmic bath, the trace distance saturates, while for Ohmic or sub-Ohmic baths, there is a finite …
Thermally Controlled Preferential Molecular Aggregation State In A Thiacarbocyanine Dye, Rémy Passier, James P. Ritchie, Carlos Toro, Carlos Diaz, Artëm E. Masunov, Kevin D. Belfield, Florencio E. Hernandez
Thermally Controlled Preferential Molecular Aggregation State In A Thiacarbocyanine Dye, Rémy Passier, James P. Ritchie, Carlos Toro, Carlos Diaz, Artëm E. Masunov, Kevin D. Belfield, Florencio E. Hernandez
Faculty Bibliography 2010s
Herein we report the experimental and theoretical study of the temperature dependence of a thiacarbocyanine dye in its monomer, H- and J-aggregates states. We demonstrate the ability to control the ratio of monomer, H- and/or J-aggregates with heat. We link such a control to the conformation dependence of the molecule. An alternative way to gain access to the dominating species without changing the concentration as a complete switching mechanism between all the present species is proposed. The results presented in this work lead to a better understanding of thiacarbocyanine dye's behavior.
Unidirectional Nonlinear Pt-Symmetric Optical Structures, Hamidreza Ramezani, Tsampikos Kottos, Ramy El-Ganainy, Demetrios N. Christodoulides
Unidirectional Nonlinear Pt-Symmetric Optical Structures, Hamidreza Ramezani, Tsampikos Kottos, Ramy El-Ganainy, Demetrios N. Christodoulides
Faculty Bibliography 2010s
We show that nonlinear optical structures involving a balanced gain-loss profile can act as unidirectional optical valves. This is made possible by exploiting the interplay between the fundamental symmetries of parity (P) and time (T), with optical nonlinear effects. This unidirectional dynamics is specifically demonstrated for the case of an integrable PT-symmetric nonlinear system.
Low-Energy Electron-Impact Ionization Of The Helium Atom Using The Multiconfiguration Hartree-Fock Method, Hari P. Saha
Low-Energy Electron-Impact Ionization Of The Helium Atom Using The Multiconfiguration Hartree-Fock Method, Hari P. Saha
Faculty Bibliography 2010s
We have extended the multiconfiguration Hartree-Fock method for electron-impact ionization of atoms to investigate the effects of polarization and electron correlation of the target in the initial state. As a test case, the method is applied to calculate triple differential cross sections for electron-impact ionization of He atom at an excess energy of 2 eV for the coplanar theta(12) = pi geometry for equal and unequal energies of two final-state outgoing electrons. To determine the effects of electron correlation between the two outgoing electrons in the final state, the variationally determined screening potential approximation is used. It is found that …
Pt Optical Lattices And Universality In Beam Dynamics, Mei C. Zheng, Demetrios N. Christodoulides, Ragnar Fleischmann, Tsampikos Kottos
Pt Optical Lattices And Universality In Beam Dynamics, Mei C. Zheng, Demetrios N. Christodoulides, Ragnar Fleischmann, Tsampikos Kottos
Faculty Bibliography 2010s
Beam dynamics in synthetic optical media with PT symmetries imposed by a balanced arrangement of gain or loss is investigated. We find that the beam power evolution is insensitive to microscopic details of the system and that it follows three distinct universal laws which depend only on the magnitude of the gain or loss parameter. Our theoretical calculations are confirmed numerically for the experimentally realizable case of a lattice consisting of coupled PT-symmetric dimers