Showing papers on "Ground state published in 2003"

Atomic Data for Resonance Absorption Lines. III. Wavelengths Longward of the Lyman Limit for the Elements Hydrogen to Gallium

Abstract: This compilation revises the 1991 listing of atomic data for the lighter elements from hydrogen to gallium. The tabulation emphasizes resonance lines, i.e., lines whose lower level is the ground state, or an excited fine-structure state of the ground term, and is restricted to wavelengths longward of the H I Lyman limit at 911.753 ?. All but the very weakest known and predicted electric-dipole transitions are included, but no forbidden lines. This paper has attempted to review all data published by the end of 2002.?????The tables contain the best data available to the author on ionization potentials, level designations, vacuum and air wavelengths, lower and upper energy levels, statistical weights, transition probabilities, natural damping constants (reciprocal lifetimes), oscillator strengths, and the often used combinations of log gf and log ?f. All ion stages with relevant classified lines are included. Individual components resulting from isotope shift and hyperfine structure are listed explicitly for certain species. The accompanying text provides references, explanations for the critical selection of data, and notes indicating where new measurements or calculations are needed.?????This compilation should be particularly useful in the analysis of interstellar and quasar absorption lines and other astrophysical sites where the density of particles and radiation is low enough to excite only the lowest atomic levels. The data also are relevant to the study of stellar atmospheres, and gaseous nebulae.?????An Appendix summarizes new data relevant to the similar compilation in Paper II for the elements germanium to uranium.

Systematic behaviour in trivalent lanthanide charge transfer energies

Abstract: Information on the energy that is needed to transfer an electron from the valence band of an inorganic compound to a trivalent lanthanide impurity is presented. The energy is a measure of the location of the ground state of the divalent lanthanide relative to the top of the valence band. A variation with type of lanthanide is found that is the same irrespective of the type of compound (fluorides, chlorides, bromides, iodides, oxides, sulfides). The variation is anti-correlated with the known variation in fd transition energies in divalent lanthanides. Because of the anti-correlation, the energy difference between the first 4fn−15d state and the bottom of the conduction band is relatively invariant with type of lanthanide ion. The difference is largest for Eu2+, and decreases gradually towards the end of the lanthanide series by 0.5 eV for Y b2+. Based on the systematic variation in charge transfer energy and fd energy, a three-parameter model is presented to position the energy levels for each divalent lanthanide relative to valence and conduction band states. Using a similar model the levels of trivalent lanthanides are positioned.

Nanometre-scale displacement sensing using a single electron transistor

Abstract: It has been a long-standing goal to detect the effects of quantum mechanics on a macroscopic mechanical oscillator. Position measurements of an oscillator are ultimately limited by quantum mechanics, where 'zero-point motion' fluctuations in the quantum ground state combine with the uncertainty relation to yield a lower limit on the measured average displacement. Development of a position transducer, integrated with a mechanical resonator, that can approach this limit could have important applications in the detection of very weak forces, for example in magnetic resonance force microscopy and a variety of other precision experiments. One implementation that might allow near quantum-limited sensitivity is to use a single electron transistor (SET) as a displacement sensor: the exquisite charge sensitivity of the SET at cryogenic temperatures is exploited to measure motion by capacitively coupling it to the mechanical resonator. Here we present the experimental realization of such a device, yielding an unequalled displacement sensitivity of 2 x 10(-15) m x Hz(-1/2) for a 116-MHz mechanical oscillator at a temperature of 30 mK-a sensitivity roughly a factor of 100 larger than the quantum limit for this oscillator.

Glassy ferromagnetism and magnetic phase separation in La 1 − x Sr x CoO 3

Abstract: We present the results of a comprehensive investigation of the dc magnetization, ac susceptibility, and magnetotransport properties of the glassy ferromagnet ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{CoO}}_{3}.$ The compositions studied span the range from the end-member ${\mathrm{LaCoO}}_{3}$ $(x=0.0)$ through to $x=0.7.$ These materials have attracted attention recently, primarily due to the spin-state transition phenomena in ${\mathrm{LaCoO}}_{3}$ and the unusual nature of the magnetic ground state for finite x. In this paper we present a consistent picture of the magnetic behavior of ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{CoO}}_{3}$ in terms of short-range ferromagnetic ordering and intrinsic phase separation. At high Sr doping $(xg0.2)$ the system exhibits unconventional ferromagnetism (with a Curie temperature up to 250 K), which is interpreted in terms of the coalescence of short-range-ordered ferromagnetic clusters. Brillouin function fits to the temperature dependence of the magnetization as well as high-temperature Curie-Weiss behavior suggest that the ${\mathrm{Co}}^{3+}$ and ${\mathrm{Co}}^{4+}$ ions are both in the intermediate spin state. At lower Sr doping $(xl0.18)$ the system enters a mixed phase that displays the characteristics of both a spin glass and a ferromagnet. A cusp in the zero-field-cooled dc magnetization, a frequency-dependent peak in the ac susceptibility and time-dependent effects in both dc and ac magnetic properties all point towards glassy behavior. On the other hand, field cooling results in a relatively large ferromagneticlike moment, with zero-field-cooled and field-cooled magnetizations bifurcating at an irreversibility point. Even in the region above $x=0.2$ the out-of-phase component of the ac susceptibility shows frequency-dependent peaks below the Curie temperature (indicative of glassy behavior) which have previously been interpreted in terms of the freezing of clusters. All of the results are consistent with the existence of a strong tendency towards magnetic phase separation in this material, a conclusion which is further reinforced by consideration of the electronic properties. The metal-insulator transition is observed to be coincident with the onset of ferromagnetic ordering $(x=0.18)$ and has a behavior in the doping dependence of the low-temperature conductivity which is strongly suggestive of percolation. This can be interpreted as a percolation transition within the simple ferromagnetic cluster model. On the metallic side of the transition the system exhibits colossal magnetoresistance-type behavior with a peak in the negative magnetoresistance (\ensuremath{\sim}10% in 90 kOe) in the vicinity of the Curie temperature. As the transition is approached from the metallic side we observe the onset of a negative magnetoresistance that increases in magnitude with decreasing temperature, reaching values as large as 90% in a 90-kOe field. This magnetoresistance is enhanced at the metal-insulator transition, where it persists even to room temperature.

Geometry optimizations with the coupled-cluster model CC2 using the resolution-of-the-identity approximation

Abstract: An implementation of the gradient for the second-order coupled-cluster singles-and-doubles model CC2 is reported, which employs the resolution-of-the-identity (RI) approximation for electron repulsion integrals. The performance of the CC2 model for ground state equilibrium geometries and harmonic frequencies is investigated and compared with experiment and other ab initio methods. It is found that CC2 equilibrium geometries have a similar accuracy to those calculated with second-order Moller–Plesset perturbation theory (MP2), but the bond lengths are larger. In particular, double and triple bonds and bonds in electron-rich compounds are elongated by 0.5–1.5 pm. Thereby CC2 slightly outperforms MP2 for single bonds, in particular in electron-rich compounds, but for strong double and triple bonds CC2 is somewhat inferior to MP2. The results for harmonic frequencies go in parallel with the results for equilibrium structures. The error introduced by the RI approximation is found to be negligible compared to t...

Analytic gradients for excited states in the coupled-cluster model CC2 employing the resolution-of-the-identity approximation

Abstract: The derivation and implementation of excited state gradients is reported for the approximate coupled-cluster singles and doubles model CC2 employing the resolution-of-the-identity approximation for electron repulsion integrals. The implementation is profiled for a set of examples with up to 1348 basis functions and exhibits no I/O bottlenecks. A test set of sample molecules is used to assess the performance of the CC2 model for adiabatic excitation energies, excited state structure constants and vibrational frequencies. We find very promising results, especially for adiabatic excitation energies, though the need of a single-reference ground state and a single-replacement dominated excited state puts some limits on the applicability of the method. Its reliability, however, can always be tested on grounds of diagnostic measures. As an example application, we present calculations on the π*←π excited state of trans-azobenzene.

Bose–Einstein condensation of the triplet states in the magnetic insulator TlCuCl3

Abstract: Bose–Einstein condensation denotes the formation of a collective quantum ground state of identical particles with integer spin or intrinsic angular momentum. In magnetic insulators, the magnetic properties are due to the unpaired shell electrons that have half-integer spin. However, in some such compounds (KCuCl3 and TlCuCl3), two Cu2+ ions are antiferromagnetically coupled1 to form a dimer in a crystalline network: the dimer ground state is a spin singlet (total spin zero), separated by an energy gap from the excited triplet state (total spin one). In these dimer compounds, Bose–Einstein condensation becomes theoretically possible2. At a critical external magnetic field, the energy of one of the Zeeman split triplet components (a type of boson) intersects the ground-state singlet, resulting in long-range magnetic order; this transition represents a quantum critical point at which Bose–Einstein condensation occurs. Here we report an experimental investigation of the excitation spectrum in such a field-induced magnetically ordered state, using inelastic neutron scattering measurements of TlCuCl3 single crystals. We verify unambiguously the theoretically predicted3 gapless Goldstone mode characteristic of the Bose–Einstein condensation of the triplet states.

Quantum Spin Chain, Toeplitz Determinants and Fisher-Hartwig Conjecture

Abstract: We consider one-dimensional quantum spin chain, which is called XX model, XX0 model or isotropic XY model in a transverse magnetic field. We study the model on the infinite lattice at zero temperature. We are interested in the entropy of a subsystem [a block of L neighboring spins]. It describes entanglement of the block with the rest of the ground state. G. Vidal, J.I. Latorre, E. Rico, and A. Kitaev showed that for large blocks the entropy scales logarithmically. We prove the logarithmic formula for the leading term and calculate the next term. We discovered that the dependence on the magnetic field interacting with spins is very simple: the magnetic field effectively reduce the size of the subsystem. We also calculate entropy of a subsystem of a small size. We also evaluated Renyi and Tsallis entropies of the subsystem. We represented the entropy in terms of a Toeplitz determinant and calculated the asymptotic analytically.

Fractionalized Fermi Liquids

Abstract: In spatial dimensions d>or=2, Kondo lattice models of conduction and local moment electrons can exhibit a fractionalized, nonmagnetic state (FL(*)) with a Fermi surface of sharp electronlike quasiparticles, enclosing a volume quantized by (rho(a)-1)(mod 2), with rho(a) the mean number of all electrons per unit cell of the ground state. Such states have fractionalized excitations linked to the deconfined phase of a gauge theory. Confinement leads to a conventional Fermi liquid state, with a Fermi volume quantized by rho(a)(mod 2), and an intermediate superconducting state for the Z2 gauge case. The FL(*) state permits a second order metamagnetic transition in an applied magnetic field.

The Cavity Method at Zero Temperature

Abstract: In this note we explain the use of the cavity method directly at zero temperature, in the case of the spin glass on a lattice with a local tree like structure, which is the proper generalization of the usual Bethe lattice to frustrated problems. The computation is done explicitly in the formalism equivalent to “one step replica symmetry breaking;” we compute the energy of the global ground state, as well as the complexity of equilibrium states at a given energy. Full results are presented for a Bethe lattice with connectivity equal to three. The main assumptions underlying the one step cavity approach, namely the existence of many local ground states, are explicitely stated and discussed: some of the main obstacles towards a rigorous study of the problem with the cavity method are outlined.

Multiple temperature regimes of radiative decay in CdSe nanocrystal quantum dots: Intrinsic limits to the dark-exciton lifetime

Abstract: We investigate the strongly temperature-dependent radiative lifetime of electron–hole excitations in colloidal CdSe nanocrystal quantum dots over nearly three orders of magnitude in temperature (300 K to 380 mK). These studies reveal an intrinsic, radiative upper limit of ∼1 μs for the storage of excitons below 2 K. At higher temperatures, exciton lifetimes are consistent with thermal activation from the dark-exciton ground state, but with two different activation thresholds.

Counterflow superfluidity of two-species ultracold atoms in a commensurate optical lattice.

Abstract: In the Mott-insulator regime, two species of ultracold atoms in an optical lattice can exhibit the low-energy counterflow motion. We construct effective Hamiltonians for the three classes of the two-species (fermion-fermion, boson-boson, and boson-fermion-type) insulators and reveal the conditions when the resulting ground state supports super-counter-fluidity (SCF), with the alternative being phase segregation. We emphasize a crucial role of breaking the isotopic symmetry between the species for realizing the SCF phase.

Extension of Bogoliubov theory to quasicondensates

Abstract: We present an extension of the well-known Bogoliubov theory to treat low-dimensional degenerate Bose gases in the limit of weak interactions and low density fluctuations. We use a density-phase representation and show that a precise definition of the phase operator requires a space discretization in cells of size l. We perform a systematic expansion of the Hamiltonian in terms of two small parameters, the relative density fluctuations inside a cell and the phase change over a cell. The resulting macroscopic observables can be computed in one, two, and three dimensions with no ultraviolet or infrared divergence. Furthermore, this approach exactly matches Bogoliubov's approach when there is a true condensate. We give the resulting expressions for the equation of state of the gas, the ground state energy, and the first order and second order correlation functions of the field. Explicit calculations are done for homogeneous systems.

Concentration-Dependent Near-Infrared to Visible Upconversion in Nanocrystalline and Bulk Y2O3:Er3+

Abstract: We investigated the upconversion properties of nanocrystalline and bulk Y2O3:Er3+ as a function of the erbium concentration (1, 2, 5, 10, 25, and 35 mol %). Following excitation with 980 nm, upconverted emission is observed from the 2H11/2, 4S3/2, and 4F9/2 excited states to the 4I15/2 ground state centered at 525, 550, and 660 nm, respectively. As the dopant concentration is increased, the upconverted luminescence revealed not only an overall increase in intensity but also an enhancement of the red (4F9/2 → 4I15/2) emission with respect to the green (2H11/2, 4S3/2 → 4I15/2) emission. A cross-relaxation process is involved in populating the 4F9/2 state, which bypasses the green-emitting states. Blue upconversion, observed in bulk Y2O3:Er3+ only, also showed a concentration dependence. The population of the 2P3/2 state was achieved through a three-step phonon-assisted energy-transfer process.

MLCT state structure and dynamics of a copper(I) diimine complex characterized by pump-probe X-ray and laser spectroscopies and DFT calculations.

Abstract: The molecular structure and dynamics of the photoexcited metal-to-ligand-charge-transfer (MLCT) state of [CuI(dmp)2]+, where dmp is 2,9-dimethyl-1,10-phenanthroline, in acetonitrile have been investigated by time-domain pump-probe X-ray absorption spectroscopy, femtosecond optical transient spectroscopy, and density functional theory (DFT). The time resolution for the excited state structural determination was 100 ps, provided by single X-ray pulses from a third generation synchrotron source. The copper ion in the thermally equilibrated MLCT state has the same oxidation state as the corresponding copper(II) complex in the ground state and was found to be penta-coordinate with an average nearest neighbor Cu−N distance 0.04 A shorter than that of the ground state [CuI(dmp)2]+. The results confirm the previously proposed “exciplex” structure of the MLCT state in Lewis basic solvents. The evolution from the photoexcited Franck-Condon MLCT state to the thermally equilibrated MLCT state was followed by femtosec...

Controlling the accuracy of the density-matrix renormalization-group method: The dynamical block state selection approach

Abstract: We have applied the momentum space version of the density-matrix renormalization-group method (k-DMRG) in quantum chemistry in order to study the accuracy of the algorithm in this new context. We have shown numerically that it is possible to determine the desired accuracy of the method in advance of the calculations by dynamically controlling the truncation error and the number of block states using a novel protocol that we dubbed dynamical block state selection protocol. The relationship between the real error and truncation error has been studied as a function of the number of orbitals and the fraction of filled orbitals. We have calculated the ground state of the molecules CH 2 , H 2 O, and F 2 as well as the first excited state of CH 2 . Our largest calculations were carried out with 57 orbitals, the largest number of block states was 1500-2000, and the largest dimensions of the Hilbert space of the superblock configuration was 800 0000-1 200 000.

Cluster expansion method for adsorption: Application to hydrogen chemisorption on graphene

Abstract: A systematic method is presented for determining the ground state of absorbed species on a substrate based on a cluster expansion of the configurational energy. It is shown that the method can determine the ground state of a strongly relaxing system using a few first-principles total energy calculations of small cells only. The method is applied to a particularly challenging case, the two-sided hydrogen chemisorption on a free standing graphene sheet, where, as a function of hydrogen coverage, the carbon hybridization goes from ${\mathrm{sp}}^{2}$ to ${\mathrm{sp}}^{3}.$ The method should require still fewer calculations and yield still more accurate results in the case of physisorption where longer-ranged strain effects are less important.

Ultrafast Internal Conversion of Excited Cytosine via the Lowest ππ* Electronic Singlet State

Abstract: Computational evidence at the CASPT2 level supports that the lowest excited state pipi* contributes to the S1/S0 crossing responsible for the ultrafast decay of singlet excited cytosine. The computed radiative lifetime, 33 ns, is consistent with the experimentally derived value, 40 ns. The nOpi* state does not play a direct role in the rapid repopulation of the ground state; it is involved in a S2/S1 crossing. Alternative mechanisms through excited states pisigma* or nNpi* are not competitive in cytosine.

The Only Stable State of O2- Is the X 2Πg Ground State and It (Still!) Has an Adiabatic Electron Detachment Energy of 0.45 eV

Abstract: The ultraviolet photoelectron spectrum of O2- exhibits 29 resolved vibronic transitions to the three low-lying electronic states of neutral O2 (X 3Σg-, a 1Δg, b 1Σg+) from the X 2ΠJ (J = 3/2 and 1/2) spin−orbit states of the anion. A Franck−Condon simulation, using the established molecular constants of the neutral oxygen states, matches every observed feature in the spectrum. The 0−0 origin transition is unambiguously assigned, yielding the electron affinity EA0(O2) = 0.448 ± 0.006 eV. The derived bond dissociation energy is D0(O2-) = 395.9 ± 0.6 kJ/mol. Coupled-cluster theory at the CCSD(T)/aug-cc-pVTZ level is used to determine the potential energy curves of O2 and of O2- in its ground state and two excited states, in both the electronically bound and unbound regions. Stabilization methods are employed to characterize the anion curves at bond lengths where their electronic energies lie above that of the ground-state neutral. The calculations confirm that the O2- X 2Πg ground state is adiabatically stab...

A Low-Spin d5 Iron Imide: Nitrene Capture by Low-Coordinate Iron(I) Provides the 4-Coordinate Fe(III) Complex [PhB(CH2PPh2)3]Fe⋮N-p-tolyl

Abstract: Entry into “[PhBP3]Fe” chemistry affords a rare, pseudotetrahedral iron(I) complex, [PhBP3]Fe(PPh3), with an S = 3/2 ground state. This precursor undergoes rapid oxidation by aryl azide to produce the d5 imide [PhBP3]Fe⋮NAr (Ar = p-tolyl). The Fe(III) imide is significant in that it is low-spin and represents the first mononuclear imide of iron. Doublet [PhBP3]Fe⋮NAr reacts rapidly and quantitatively with CO at room temperature to release isocyanate and [PhBP3]Fe(CO)2. The [PhBP3]Fe(CO)2 byproduct is also a precursor to [PhBP3]Fe⋮NAr upon addition of aryl azide.

Laser Cooling of Trapped Ions

Abstract: Laser cooling was first proposed in 1975 by Hansch and Schawlow, and simultaneously by Wineland and Dehmelt. After some general remarks on laser cooling in traps we report on experiments featuring two special laser cooling techniques for ions which are stored in Paul traps. With both techniques we demonstrate ground state cooling of a single trapped ion. Ground state cooling of one or a string of ions might help to improve ion-based frequency standards, and is a prerequisite for an ion-based quantum processor.

Interaction of C60 with carbon nanotubes and graphite.

Abstract: The interaction of C60 with single-wall carbon nanotubes (SWNTs) and graphite is studied experimentally by thermal desorption spectroscopy and theoretically by molecular-mechanics and molecular-dynamics calculations. The van der Waals parameters and force field for C60-graphene and C60-SWNT interactions are derived from the low-coverage C60 binding energy to the graphite surface. We use these to compare the efficiency of different mechanisms by which C60 can be encapsulated into SWNTs.

Magnetism in all-carbon nanostructures with negative Gaussian curvature.

Abstract: We apply the ab initio spin density functional theory to study magnetism in all-carbon nanostructures. We find that particular systems, which are related to schwarzite and contain no undercoordinated carbon atoms, carry a net magnetic moment in the ground state. We postulate that, in this and other nonalternant aromatic systems with negative Gaussian curvature, unpaired spins can be introduced by sterically protected carbon radicals.

Ground-state phase diagram of S = 1 XXZ chains with uniaxial single-ion-type anisotropy

Abstract: One-dimensional $S=1$ $\mathrm{XXZ}$ chains with uniaxial single-ion-type anisotropy are studied by numerical exact diagonalization of finite-size systems. The numerical data are analyzed using conformal field theory, the level spectroscopy, phenomenological renormalization-group, and finite-size scaling method. We thus present a quantitatively reliable ground-state phase diagram of this model. The ground states of this model contain the Haldane phase, large-D phase, N\'eel phase, two $\mathrm{XY}$ phases, and the ferromagnetic phase. There are four different types of transitions between these phases: the Brezinskii-Kosterlitz-Thouless-type transitions, the Gaussian-type transitions, the Ising-type transitions, and the first-order transitions. The locations of these critical lines are accurately determined.

Patterned loading of a Bose-Einstein condensate into an optical lattice

Abstract: Neutral atoms confined in an array of magnetic or optical traps offer a scalable system for quantum information processing. Several proposals @1‐3# for providing the required coherent control of the states of individual atoms and their interactions involve optical lattices, periodic light-shift potentials produced by optical standing waves. Ideally, the lattice should be able to separate the atoms ~qubits! by more than an optical wavelength ~to allow individual optical addressing! while confining each atom to a region much smaller than an optical wavelength. Tight confinement is important in most of these proposals both to increase the interaction strength between atoms in a site @1,2# and to decrease the oscillation period, which sets the time scale for moving atoms. Here we experimentally demonstrate a technique to selectively load atoms into the motional ground state of every third site of a one-dimensional ~1D! optical lattice. This technique involves the sequential application of two independent lattices whose spatial periods differ by a factor of 3. We use the resulting ‘‘superlattice’’ to transfer atoms in a BoseEinstein condensate ~BEC! from the long-period lattice sites to the coinciding sites of the short-period lattice. The final state provides the tight confinement of the short-period lattice with a separation three times larger than the lattice period. Large separation between sites can also be achieved by using CO2 lasers @4# or arrays of optical dipole traps @5#, but these techniques require much more laser power to provide similar confinement. Patterned loading adds versatility to the atom-lattice architecture, and empty sites between atoms are in fact necessary for quantum computing proposals such as Ref. @1#. While the present experiment involves many atoms in every third plane of a single 1D lattice site, the technique can be extended to other fractional fillings and to 3D lattices, which could have single atoms in individual sites. We create each of the lattices by intersecting two laser beams at an angle u i ~see Fig. 1!. The lattice period di 5l/@2 sin(ui/2)#, where l52p/k is the laser wavelength. In this experiment, the u i are chosen such that the periods differ by a factor of 3, resulting in parallel lattices with periods of dl51.5 mm ~long lattice! and ds50.5 mm ~short lattice!. The light-shift potential is given by U~ z!52 Ul

Description of the ground state wave functions of Ni dithiolenes using sulfur K-edge X-ray absorption spectroscopy.

Abstract: The pterin-dithiolene cofactor is an essential component of the catalytic sites of all molybdoenzymes except nitrogenase. Understanding its bonding to transition metals allows for development of electronic structure/function correlations in catalysis. The electronic structure description for a series of bis(dithiolene) complexes ([NiL2]Z, L = 1,2-Me2C2S2; Z = 2−, 1−, 0) using sulfur XAS provides the basis for extension to the biologically relevant metal-containing dithiolenes. The transition dipole integral has been developed for the dithiolene sulfur through correlation of XAS pre-edge energy positions of sulfide-, thiolate-, and enedithiolate-S. The ground state wave functions of all three NiL2 complexes have more than 50% S character experimentally demonstrating the noninnocent behavior of the dithiolene ligand. The S K-edge experimental results are correlated with spin-unrestricted, broken-symmetry density functional calculations. These show only limited spin polarization in the neutral complex and de...

Kondo effect in the presence of itinerant-electron ferromagnetism studied with the numerical renormalization group method.

Abstract: The Kondo effect in quantum dots (QDs)-artificial magnetic impurities-attached to ferromagnetic leads is studied with the numerical renormalization group method. It is shown that the QD level is spin split due to the presence of ferromagnetic electrodes, leading to a suppression of the Kondo effect. We find that the Kondo effect can be restored by compensating this splitting with a magnetic field. Although the resulting Kondo resonance then has an unusual spin asymmetry with a reduced Kondo temperature, the ground state is still a locally screened state, describable by Fermi liquid theory and a generalized Friedel sum rule, and transport at zero temperature is spin independent.