Adiabatic Interaction Research Articles

The essential ingredients leading to the explosive growth stage of the European wind storm Lothar of Christmas 1999

AbstractKey dynamical ingredients leading to the explosive growth stage of the extratropical wind storm Lothar (24–26 December 1999) are identified by performing numerical sensitivity experiments using the Météo‐France operational model. This stage suddenly occurred when the surface cyclone crossed the upper‐level jet in its exit region. The model is shown to capture quite well the whole process by starting the forecast 12 h before the start of the explosive growth stage.A first set of experiments consists of revisiting the role of humidity and other physical processes. A run suppressing latent heating does not exhibit any cyclone growth, similar to a previous study by other authors. However, a frictionless dry adiabatic run, i.e. when latent heating processes and dissipation terms are both suppressed, is shown to reproduce the timing and the location of the rapid intensification stage but not its intensity (which is overestimated). Moist processes are thus crucial because they compensate for the dissipation terms, but the vertical coupling between the surface cyclone and the upper‐level jet can be reproduced and interpreted in terms of frictionless dry adiabatic interactions, at least for conceptual purposes.All the other numerical experiments have the full physics of the model and only differ in their initial conditions. The modification of the flow is performed using a recently developed potential vorticity inversion method. Upper‐level high‐frequency anomalies are shown to have only a moderate impact on the rapid deepening of the surface cyclone. Other experiments are conducted to look at the sensitivity to the strength of the upper‐level jet, to the intensity of the low‐level baroclinicity, to the location of the jet exit and finally to the shape, amplitude and location of the low‐level cyclone. The location of the explosive growth stage depends primarily on the position of the low‐frequency jet exit while its intensity and even its existence is strongly sensitive to the low‐level background baroclinicity and to the properties of the incipient surface cyclone itself. Copyright © 2010 Royal Meteorological Society

State selection in nonresonantly excited wave packets by tuning from nonadiabatic to adiabatic interaction

We show for rotational alignment of diatomic molecules that the crossover from nonadiabatic to adiabatic limits is well described by a convolution of excitation pulse envelope and sinusoidal molecular response and that it takes place in a uniform way in the region between 0.1 and 1 for the ratio of pulse duration to rotational period. In a nonresonant Raman-type excitation, this crossover is used to manipulate the $J$ composition of a rotational wave packet with respect to the initial thermal distribution. By optimizing the duration of a single pulse, arbitrarily narrow distributions at low $J$ levels can be formed. A double-pulse excitation, where a longer second pulse acts as a selective dump pulse, allows to prepare nonthermal distributions centered at high $J$ values. With the alignment signal on top of an isotropic background, experimental techniques sensitive to the induced anisotropy are optimally suited for implementation. To demonstrate the efficiency of the method, numerical simulations are carried out for rotational alignment in ${^{14}\text{N}}_{2}$ at various experimentally relevant laser intensities. The scheme is transferable to quantum systems with a significant variation in transition frequencies between subsequent levels.

Generalized perturbed complex Toda chain for Manakov system and exact solutions of Bose–Einstein mixtures

We analyze, both analytically and numerically, the dynamical behavior of the N-soliton train in the Manakov system with perturbations due to an external potential. The perturbed complex Toda chain model has been employed to describe adiabatic interactions within the N Manakov-soliton train. Simulations performed demonstrate that external potentials can play a stabilizing role to provide bound state regime of the train propagation. We also present new stationary and travelling wave solutions to equations describing Bose–Fermi mixtures in an elliptic external potential. Precise conditions for the existence of every class of solutions are derived. There are indications that such waves and localized objects may be observed in experiments with cold quantum degenerate gases.

The turbulent destruction of clouds - I. Ak-ε treatment of turbulence in 2D models of adiabatic shock-cloud interactions

The interaction of a shock with a cloud has been extensively studied in the literature, where the effects of magnetic fields, radiative cooling and thermal conduction have been considered. In many cases, the formation of fully developed turbulence has been prevented by the artificial viscosity inherent in hydrodynamical simulations. This problem is particularly severe in some recent simulations designed to investigate the interaction of a flow with multiple clouds, where the resolution of individual clouds is necessarily poor. Furthermore, the shocked flow interacting with the cloud has been assumed to be completely uniform in all previous single-cloud studies. In reality, the flow behind the shock is also likely to be turbulent, with non-uniform density, pressure and velocity structure created as the shock sweeps over inhomogeneities upstream of the cloud (as seen in recent multiple cloud simulations). To address these twin issues we use a subgrid compressible k–� turbulence model to estimate the properties of the turbulence generated in shock–cloud interactions and the resulting increase in the transport coefficients that the turbulence brings. A detailed comparison with the output from an inviscid hydrodynamical code puts these new results into context. Despite the above concerns, we find that cloud destruction in inviscid and k–� models occurs at roughly the same speed when the post-shock flow is smooth and when the density contrast between the cloud and intercloud medium, χ 100. However, there are increasing and significant differences as χ increases. The k–� models also demonstrate better convergence in resolution tests than inviscid models, a feature which is particularly useful for multiple-cloud simulations. Clouds which are over-run by a highly turbulent post-shock environment are destroyed significantly quicker as they are subject to strong ‘buffeting’ by the flow. The decreased lifetime and faster acceleration of the cloud material to the speed of the ambient flow leads to a reduction in the total amount of circulation (vorticity) generated in the interaction, so that the amount of vorticity may be self-limiting. Additional calculations with an inviscid code where the post-shock flow is given random, grid-scale, motions confirm the more rapid destruction of the cloud. Our results clearly show that turbulence plays an important role in shock–cloud interactions, and that environmental turbulence adds a new dimension to the parameter space which has hitherto been studied.

Adiabatic Interaction Leading to the Avoided Crossing between the Twin 31Δg and 41Δg Rydberg States in Na2

We present detailed investigations of our previously reported observations of the 3(1)Delta(g) and 4(1)Delta(g) Rydberg states having separated-atom limits of Na(3s) + Na(4d) and Na(3s) + Na(4f), respectively, of Na(2) using high-resolution cw optical-optical double resonance spectroscopic measurements and analyzing the assigned rovibrational energy levels both by the individual linear fit method and the Dunham polynomial fit method. We have sorted out e/f-parity observed energy levels, and then from the Dunham polynomial fits of the e-parity levels, we have derived molecular constants and constructed Rydberg-Klein-Rees potentials of the 3(1)Delta(g) and 4(1)Delta(g) states, which appear to be twin states with an avoided crossing at R(c) = 4.10 A and a splitting of DeltaE(c) = 94 cm(-1). The potentials are in good agreement with the ab initio calculations and linear fit results. The Lambda-doubling splittings and the (f-d) l-mixing are investigated. A detailed discussion is focused on the adiabatic interaction of the perturbed molecular wave functions/states causing mutual amplitude/intensity sharing giving rise to avoided crossing between the 3(1)Delta(g) and 4(1)Delta(g) states.

Electron-phonon interactions and high-temperature thermodynamics of vanadium and its alloys

Inelastic neutron scattering was used to measure the phonon densities of states (DOSs) for pure V and solid solutions of V with 6 to 7at% of Co, Nb, and Pt, at temperatures from 10 K to 1323 K. Ancillary measurements of heat capacity and thermal expansion are reported on V and V-7at%Co and used to help identify the different sources of entropy. Pure V exhibits an anomalous anharmonic stiffening of phonons with increasing temperature. This anharmonicity is suppressed by Co and Pt, but not by isoelectronic Nb solutes. The changes in phonon frequency with alloying and with temperature both correlate to the decrease in electron density of states (DOS) at the Fermi level as calculated using density functional theory. The effects of both temperature and alloying can be understood in terms of an adiabatic electron-phonon interaction (EPI), which broadens sharp features in the electron DOS. These results show that the adiabatic EPI can influence the phonon thermodynamics at temperatures exceeding 1000 K, and that thermal trends of phonons may help assess the strength of the EPI.

Quantum Signatures of Chaos in Adiabatic Interaction Between a Trapped Ion and a Laser Standing Wave

We study quantum motion around a classical heteroclinic point of a single trapped ion interacting with a strong laser standing wave. We construct a set of exact coherent states of the quantum system and from the exact solutions reveal that quantum signatures of chaos can be induced by the adiabatic interaction between the trapped ion and the laser standing wave, where the quantum expectation values of position and momentum correspond to the classically chaotic orbit. The chaotic region on the phase space is illustrated. The energy crossing and quantum resonance in time evolution and the exponentially increased Heisenberg uncertainty are found. The results suggest a theoretical scheme for controlling the unstable regular and chaotic motions.

N-soliton interactions of Bose-Einstein condensates in external potentials

In this paper, a perturbed complex Toda chain has been employed to describe the adiabatic interactions in an N-soliton train of the Gross-Pitaevskii equation. Perturbations induced by weak quadratic and periodic external potentials are analytically and numerically studied. It is found that the perturbed complex Toda chain adequately models the N-soliton train dynamics for both types of potentials. As an application of the developed theory, we consider the dynamics of a train of matter-wave solitons confined in a quadratic trap and optical lattice, as well as tilted periodic potentials. In the last case, we demonstrate that there exist critical values of the strength of the linear or periodic potential for which one or more localized states can be extracted from a soliton train. In addition, some interesting results in the experiments and applications of the Bose-Einstein condensates are also obtained.

AdiabaticN-soliton interactions of Bose-Einstein condensates in external potentials

A perturbed version of the complex Toda chain (CTC) has been employed to describe adiabatic interactions within an N-soliton train of the nonlinear Schrödinger equation. Perturbations induced by weak quadratic and periodic external potentials are studied by both analytical and numerical means. It is found that the perturbed CTC adequately models the N-soliton train dynamics for both types of potentials. As an application of the developed theory, we consider the dynamics of a train of matter-wave solitons confined to a parabolic trap and optical lattice, as well as tilted periodic potentials. In the last case, we demonstrate that there exist critical values of the strength of the linear potential for which one or more localized states can be extracted from a soliton train. An analytical expression for these critical strengths for expulsion is also derived.

Van der Waals interactions and dipole polarizabilities of lanthanides: Tm(F2)–He and Yb(S1)–He potentials

Anisotropic dipole polarizabilities of Tm(2F), Tm+2(2F), and Yb(1S) are calculated using the finite-field multireference averaged quadratic coupled cluster (MR-AQCC) (Tm and Tm+2) and RCCSD(T) (Yb) methods with small-core relativistic pseudopotentials ECP28MWB combined with the augmented ANO basis sets. The lanthanide atoms are strongly polarizable with the scalar part originating from the 6s electrons and the tensorial part from the open 4f shells. The adiabatic interaction potentials 2Sigma+, 2Pi, 2Delta, and 2Phi of Tm(2F)-He and Tm+2(2F)-He were examined by the multireference approaches, multireference configuration interaction and MR-AQCC, using the basis sets designed in the polarizability calculations. A closed-shell lanthanide system Yb(1S)-He was included for comparison. The Tm-He 2Sigma+, 2Pi, 2Delta, and 2Phi interaction potentials are very shallow and nearly degenerate (within 0.01 cm(-1)), with the well depths in the range of 2.35-2.36 cm(-1) at R=6.17 A. The basis-set saturated well depths are expected to be larger by ca. 25%, as estimated using the bond-function augmented basis set. The interactions of lanthanide atoms with He are one order of magnitude less anisotropic than those involving first-row transition metal atoms. The suppression of anisotropy is chiefly attributed to the screening effected by the 6s shell. When these electrons are removed as in the di-cation complex Tm+2(2F)-He, the potentials deepen to a thousand wave number range and their anisotropy is enhanced 500-fold.

Role of electron-phonon interaction on quasiparticle dispersion in the strongly correlated cuprate superconductors

The role of the electron-phonon (el-ph) interaction in high-${T}_{c}$ cuprates is investigated theoretically by considering correlated electrons interacting with Holstein phonons within the two-dimensional single-band Hubbard model in the limit of large Coulomb interaction. It is shown that the electron-phonon interaction gives rise to a kink in the dispersion along the nodal direction and to a peak/dip/hump structure in the one-electron spectral weight whose dependence on temperature, isotope substitution, and doping is discussed in relation to recent photoemission experiments on the nodal quasiparticles in Bi2201 and LSCO. A comparison with these experiments shows that electron correlations play a crucial role in the determination of the kink position, size, and doping dependence. We also show that the ``unusual'' oxygen isotope shift in the real part of the self-energy, experimentally observed in the optimally doped Bi2212 samples, can be qualitatively explained within the framework that incorporates both strong electron correlations and the adiabatic electron-phonon interaction.

Modeling Adiabatic N-Soliton Interactions and Perturbations

We analyze a perturbed version of the complex Toda chain (CTC) in an attempt to describe the adiabatic N-soliton train interactions of the perturbed nonlinear Schrodinger equation. We study perturbations with weak quadratic and periodic external potentials analytically and numerically. The perturbed CTC adequately models the N-soliton train dynamics for both types of potentials. As an application of the developed theory, we consider the dynamics of a train of matter-wave solitons confined in a parabolic trap and an optical lattice.

Coherent momentum transfer due to interaction between three-level atoms and counterpropagating laser pulses

A theoretical analysis is presented of the change in the momentum of a three-level atom due to its interaction with counterpropagating laser pulses that overlap in time. The two lower energy states of the atom are metastable; i.e., a lambda-type configuration of atomic levels is considered. The cases of two and four counterpropagating pulses having different carrier frequencies are considered. In the case of adiabatic atom-field interaction, it is shown that the atom’s momentum can change by an integer multiple of the photon momentum and the corresponding standard deviation is small as compared to the photon momentum squared.

Interactions of transition metal atoms with He

The adiabatic interaction potentials were obtained for the paradigm transition metal-rare gas interactions: Sc(2D)-He and Ti(3F)-He and their di-cations. The ab initio approach included the coupled cluster and multireference configuration interaction methods. He atoms form very weak van der Waals complexes with Sc and Ti with well-depths of ca. 4-5 cm-1. The interactions are characterized by the nearly-degenerate manifolds of adiabatic states with splittings of the order of 0.1 cm-1 or less. The anisotropy of the Ti-He interaction is smaller than that for the Sc-He interaction. The origin of the weak anisotropy of these interactions was analyzed. The exchange repulsion was found to be nearly the same in the \({\rm\Sigma}\), \({\rm\Pi}\) and \({\rm\Delta}\) states due to the valence d-electrons being submerged under the doubly filled 4s electron sub-shell. The anisotropy of the total potential is controlled by the weakly-anisotropic dispersion interaction.

Theoretical ab initio study on the electronic states of GaO and Ga 2O

Potential energy curves have been calculated for the ground and excited doublet and quartet states of the radical gallium monoxide. The ground state, X 2 Σ +, is found to have a minimum at 1.65 Å with a well-depth of 4.65 eV, while the lowest excited state, A 2Π is found to lie very close to the ground state, at ν 00 of 4204 cm −1 with r min at 1.803 Å and a well depth of 4.06 eV. The next excited state, B 2 Σ +, which is the only excited state for which there is published experimental information, is well separated from the two lower states, with a shallow minimum of 1.81 eV calculated at 1.706 Å. Non adiabatic interactions between the three lowest electronic states of GaO are weak, and there is no significant mixing of the vibrational levels of the X 2 Σ + and A 2Π caused by rotational-electronic coupling, even for very high values of the rotational quantum number N. The present calculations support the earlier reported values for the rotational constants of the X 2 Σ + and the B 2 Σ + states rather than those of the more recent findings. Symmetric stretch potentials have been calculated for electronic states of the Gallium suboxide (Ga 2O) molecule at linear geometries. The first excited state, A 1Π u, is calculated at 5.03 eV above the ground electronic state, X 1 Σ g +. The ground state and most of the excited states of Ga 2O have minima at linear geometries.

On adiabatic N-soliton interactions and trace identities

We compare the Hamiltonian properties of the N-soliton solutions of the NLSE in the adiabatic approximation and show how it matches the Hamiltonian formulation for the complex Toda chain which describes the adiabatic N-soliton interactions.

Radiation of a charge moving over the diffraction grating

The states of a charged particle with a finite free path are determined in the field of a resonant electromagnetic wave. The exact resonance conditions, the modulation and beam instability mechanisms, the charge and current densities (Ohm's law) are obtained for the collisionless beam of resonance particles. Quantum theory of radiation is developed for the resonant adiabatic interaction between a particle and a wave taking into account the interaction with a constant magnetic field induced at the grating surface by the charge and nonresonant waves. The radiation power, the spectrum, and the range of generated frequencies are determined. The results obtained can be used in the plasma and solid-state theories and in electronics.

Modeling of vibronic interaction and chaotic dynamics in electronic and nuclear subsystems of molecules

AbstractThe interaction of electronic and nuclear subsystems of a molecular system is described to be a consequence of cubic and biquadratic coupling on coordinates between electronic and nuclear oscillators in the classic and mixed quantum–classic models of a molecule. The simple relationships between two parameters of nonlinearity and usually used in the description of adiabatic vibronic interaction in a real molecules a shift of equilibrium position of nuclei and change of force constant them harmonic vibrations upon electronic excitation of a molecule are established. It is shown that performance of these relationships averaged on “fast” time dynamics of excitation of electronic oscillators of the classic model coincides with dynamics of population of the excited electronic state of the mixed quantum–classic model for any values of nuclear positions. The influence considered vibronic interaction on the character of dependence of quasienergies of a molecule dressed by a cloud of photons from the coordinate nuclear oscillator is investigated. As a necessary condition for the appearance of chaotic dynamics of nuclei in the considered quantum–classic model of a molecule at transformation by its light fields it is proposed to consider the occurrence of two‐well quasienergy. Taking account this criterion, it is shown that only the considered cubic (but not biquadratic) vibronic interaction is one of the reasons for the chaotic dynamics of nuclei in molecules interacting with a light field. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002

The Effective Degree of Freedom of Low Energy QCD**The project partly supported by NSF, SED and SSTD of China, and partly by the US Department of Energy under contract W-7405-ENG-36

The adiabatic effective baryon-baryon interactions and dibaryon candidates are studied systematically with three constituent quark models based on different effective degrees of freedom: Glozman–Riska–Brown Goldstone boson exchange model based on constituent quark and Goldstone boson coupling; Fujiwara model based on constituent quark gluon coupling and Nijmegen one-boson exchange; QDCSM based on constituent quark and gluon coupling with quark delocalization and color screening. We find that the three models predicted the similar effective baryon-baryon interactions for roughly two thirds among the 64 states consisted of octet and decuplet baryons. The differences among three models and their separate characteristics are also studied.

Adiabatic interaction of N ultrashort solitons: universality of the complex Toda chain model.

Using the Karpman-Solov'ev method we derive the equations for the two-soliton adiabatic interaction for solitons of the modified nonlinear Schrödinger equation (MNSE). Then we generalize these equations to the case of N interacting solitons with almost equal velocities and widths. On the basis of this result we prove that the N MNSE-soliton train interaction (N>2) can be modeled by the completely integrable complex Toda chain (CTC). This is an argument in favor of universality of the complex Toda chain that was previously shown to model the soliton train interaction for nonlinear Schrödinger solitons. The integrability of the CTC is used to describe all possible dynamical regimes of the N-soliton trains that include asymptotically free propagation of all N solitons, N-soliton bound states, various mixed regimes, etc. It allows also to describe analytically the manifolds in the 4N-dimensional space of initial soliton parameters that are responsible for each of the regimes mentioned above. We compare the results of the CTC model with the numerical solutions of the MNSE for two and three-soliton interactions and find a very good agreement.