Search results for "ROTATIONAL"
showing 10 items of 381 documents
Translational and rotational diffusion in supercooled orthoterphenyl close to the glass transition
1992
Self diffusion coefficients in supercooled orthoterphenyl (OTP) have been determined down toD t =3·10−14 m2s−1 using a1H-NMR technique applying static field gradients up to 53T m−1 In a range of more than two decades theD t values agree with those of photochromic tracer molecules of the same size determined by forced Rayleigh scattering down to the glass transition temperatureT g . A change of mechanism is found for translational diffusion atT c ≈1.2T g whereD t is proportional to the inverse shear viscosityη −1 atT>T c butD t ∼η ξ with ξ=0.75 atT<T c . Rotational correlation times determined by2H-NMR stimulated echo techniques in deuterated OTP remain proportinal toη −1 down toT g . Our re…
Symmetry, winding number, and topological charge of vortex solitons in discrete-symmetry media
2009
[EN] We determine the functional behavior near the discrete rotational symmetry axis of discrete vortices of the nonlinear Schrodinger equation. We show that these solutions present a central phase singularity whose charge is restricted by symmetry arguments. Consequently, we demonstrate that the existence of high-charged discrete vortices is related to the presence of other off-axis phase singularities, whose positions and charges are also restricted by symmetry arguments. To illustrate our theoretical results, we offer two numerical examples of high-charged discrete vortices in photonic crystal fibers showing hexagonal discrete rotational invariance
Numerical evolution of matter in dynamical axisymmetric black hole spacetimes
2000
We have developed a numerical code to study the evolution of self-gravitating matter in dynamic black hole axisymmetric spacetimes in general relativity. The matter fields are evolved with a high-resolution shock-capturing scheme that uses the characteristic information of the general relativistic hydrodynamic equations to build up a linearized Riemann solver. The spacetime is evolved with an axisymmetric ADM code designed to evolve a wormhole in full general relativity. We discuss the numerical and algorithmic issues related to the effective coupling of the hydrodynamical and spacetime pieces of the code, as well as the numerical methods and gauge conditions we use to evolve such spacetime…
The rotational gas-phase spectrum of trans- and cis-HSSOH at 100GHz
2009
Abstract We present the first pure rotational spectra of the two most stable conformers of oxatrisulfane, trans- and cis-HSSOH, in their vibrational ground state. For both conformers a-, b-, and c-type transitions have been recorded in the range from 75 to 120 GHz using an all solid-state spectrometer. More than 200 lines have been assigned for each conformer, most of them belonging to the r Q 2 - and the r Q 3 -branch of the perpendicular spectra. The least-squares fit analysis using a semirigid rotor Hamiltonian in S-reduction yields precise values for the ground-state rotational constants A 0 = 21 145.93422 ( 66 ) , B 0 = 4479.92301 ( 21 ) , C 0 = 3828.34269 ( 21 ) for cis-HSSOH, and A 0…
Magnetohydrodynamic experiments on cosmic magnetic fields
2008
It is widely known that cosmic magnetic fields, i.e. the fields of planets, stars, and galaxies, are produced by the hydromagnetic dynamo effect in moving electrically conducting fluids. It is less well known that cosmic magnetic fields play also an active role in cosmic structure formation by enabling outward transport of angular momentum in accretion disks via the magnetorotational instability (MRI). Considerable theoretical and computational progress has been made in understanding both processes. In addition to this, the last ten years have seen tremendous efforts in studying both effects in liquid metal experiments. In 1999, magnetic field self-excitation was observed in the large scale…
Microwave spectroscopy on heavy-fermion systems: probing the dynamics of charges and magnetic moments
2013
Investigating solids with light gives direct access to charge dynamics, electronic and magnetic excitations. For heavy fermions, one has to adjust the frequency of the probing light to the small characteristic energy scales, leading to spectroscopy with microwaves. We review general concepts of the frequency-dependent conductivity of heavy fermions, including the slow Drude relaxation and the transition to a superconducting state, which we also demonstrate with experimental data taken on UPd2Al3. We discuss the optical response of a Fermi liquid and how it might be observed in heavy fermions. Microwave studies with focus on quantum criticality in heavy fermions concern the charge response, …
Geometric efficiency for a parallel-surface source and detector system with at least one axisymmetric surface
2007
Abstract An exact and numerically friendly method is given to calculate the geometric efficiency G of a planar radiation source and cosine detector system. Either the source or the detector, but not necessarily both, must have axial symmetry. For two non-coaxial disks the results are in exact agreement with a recent generalization of Ruby's formula for G. Detailed formulas and sample numerical results are given for a disk combined with rectangles and triangles. A disk and a general polygon can be solved by dividing the polygon into triangles. The method can also be applied to electrical inductance calculations and a solution recently given for the inductance of circular and elliptic loops c…
Symmetry of molecular properties
1993
The symmetry of coefficients in the expansion of a given molecular property are shown to be obtainable through well defined tensor methods. The analytical expansions required of various vibrational and rotational tensors are given up to the fourth degree in dynamical variables. To illustrate the method, some rovibrational properties of spherical tops are considered. The symmetry of the associated molecular constants is expressed, simultaneously, for XY4 and XY6 molecules, by algebraic relations involving the independent constants and the coupling symbols of the molecular symmetry group. To allow comparisons, some examples are given for which the symmetry of the constants has been published …
Rotational-vibrational relative equilibria and the structure of quantum energy spectrum of the tetrahedral molecule P4
2001
We find relative equilibria (RE) of the rotating and vibrating tetrahedral molecule P4 and study the correspondence of these RE's to the extremal quantum states in the vibration-rotation multiplet and to the extrema of the semi-quantum rotational energy surfaces obtained for a number of excited vibrational states. To compute the energy of RE's we normalize the full rotation-vibration Hamiltonian H of P4 in the approximation of nonresonant modes ν E 2 and ν F_2 3 and find the stationary points of the resulting normal form (known as reduced effective Hamiltonian H eff ) which is defined on the reduced phase space CP 2 × CP 1 × S 2 . Most of these points are fixed points of the symmetry group …
A topological charge selection rule for phase singularities
2009
We present a study of the dynamics and decay pattern of phase singularities due to the action of a system with a discrete rotational symmetry of finite order. A topological charge conservation rule is identified.