The alpha-gamma transition of Cerium is entropy-driven

We emphasize, on the basis of experimental data and theoretical calculations, that the entropic stabilization of the gamma-phase is the main driving force of the alpha-gamma transition of cerium in a wide temperature range below the critical point. Using a formulation of the total energy as a functional of the local density and of the f-orbital local Green's functions, we perform dynamical mean-field theory calculations within a new implementation based on the multiple LMTO method, which allows to include semi-core states. Our results are consistent with the experimental energy differences and with the qualitative picture of an entropy-driven transition, while also confirming the appearance of a stabilization energy of the alpha phase as the quasiparticle Kondo resonance develops.Comment: 5 pages, 6 figure

Some Location and Price Equilibria in Facility Investment with Uncertain Demand

This paper describes the spatial distribution of customer demand, supply of customer services, and facility investment as the outcome of a three-level game-like interaction between customers (e.g., shoppers), suppliers (e.g., retailers) and developers (e.g., landlords). Suppliers in each center are assumed to compete with suppliers in all other centers. Similarly, the developers of each center compete with developers of all other centers. With this specification, multi-center equilibria of the Nash type are examined for suppliers on the one hand, and for developers on the other. Suppliers in a center decide about utilized floorspace and price level in the center. Developers of a center decide about available floorspace and rent level. The uncertain customer demand is specified in probabilistic terms, representing the suppliers' and developers' perception of customer behavior. An approach to estimate customer response patterns is presented and discussed

Is the Mott transition relevant to f-electron metals ?

We study how a finite hybridization between a narrow correlated band and a wide conduction band affects the Mott transition. At zero temperature, the hybridization is found to be a relevant perturbation, so that the Mott transition is suppressed by Kondo screening. In contrast, a first-order transition remains at finite temperature, separating a local moment phase and a Kondo- screened phase. The first-order transition line terminates in two critical endpoints. Implications for experiments on f-electron materials such as the Cerium alloy Ce$_{0.8}$La$_{0.1}$Th$_{0.1}$ are discussed.Comment: 5 pages, 3 figure

Average characteristic polynomials in the two-matrix model

The two-matrix model is defined on pairs of Hermitian matrices $(M_1,M_2)$ of size $n\times n$ by the probability measure $$\frac{1}{Z_n} \exp\left(\textrm{Tr} (-V(M_1)-W(M_2)+\tau M_1M_2)\right)\ dM_1\ dM_2,$$ where $V$ and $W$ are given potential functions and \tau\in\er. We study averages of products and ratios of characteristic polynomials in the two-matrix model, where both matrices $M_1$ and $M_2$ may appear in a combined way in both numerator and denominator. We obtain determinantal expressions for such averages. The determinants are constructed from several building blocks: the biorthogonal polynomials $p_n(x)$ and $q_n(y)$ associated to the two-matrix model; certain transformed functions $\P_n(w)$ and \Q_n(v); and finally Cauchy-type transforms of the four Eynard-Mehta kernels $K_{1,1}$, $K_{1,2}$, $K_{2,1}$ and $K_{2,2}$. In this way we generalize known results for the $1$-matrix model. Our results also imply a new proof of the Eynard-Mehta theorem for correlation functions in the two-matrix model, and they lead to a generating function for averages of products of traces.Comment: 28 pages, references adde

Large-scale exact diagonalizations reveal low-momentum scales of nuclei

Ab initio methods aim to solve the nuclear many-body problem with controlled approximations. Virtually exact numerical solutions for realistic interactions can only be obtained for certain special cases such as few-nucleon systems. Here we extend the reach of exact diagonalization methods to handle model spaces with dimension exceeding $10^{10}$ on a single compute node. This allows us to perform no-core shell model (NCSM) calculations for 6Li in model spaces up to $N_\mathrm{max} = 22$ and to reveal the 4He+d halo structure of this nucleus. Still, the use of a finite harmonic-oscillator basis implies truncations in both infrared (IR) and ultraviolet (UV) length scales. These truncations impose finite-size corrections on observables computed in this basis. We perform IR extrapolations of energies and radii computed in the NCSM and with the coupled-cluster method at several fixed UV cutoffs. It is shown that this strategy enables information gain also from data that is not fully UV converged. IR extrapolations improve the accuracy of relevant bound-state observables for a range of UV cutoffs, thus making them profitable tools. We relate the momentum scale that governs the exponential IR convergence to the threshold energy for the first open decay channel. Using large-scale NCSM calculations we numerically verify this small-momentum scale of finite nuclei.Comment: Minor revisions.Accepted for publication in Physical Review

Oscillator Strengths and Damping Constants for Atomic Lines in the J and H Bands

We have built a line list in the near-infrared J and H bands (1.00-1.34, 1.49-1.80 um) by gathering a series of laboratory and computed line lists. Oscillator strengths and damping constants were computed or obtained by fitting the solar spectrum. The line list presented in this paper is, to our knowledge, the most complete one now available, and supersedes previous lists.Comment: Accepted, Astrophysical Journal Supplement, tentatively scheduled for the Sep. 1999 Vol. 124 #1 issue. Text and tables also available at http://www.iagusp.usp.br/~jorge

Structure and kinematics of the molecular spiral arms in M51

Mapping of the CO(1-0) emission from the spiral galaxy was made with the Onsala 20 m antenna. The observations show that the emission is considerably enhanced in spiral arms which appear to originate as intense ridges of emission about 1 kpc from the nucleus. One of the main objectives for the 1986 observations was to study the variations of the tangential velocity component of molecular gas across a spiral arm. The radial velocity was found to have a velocity shift similar to that predicted by the density wave theory. The present (1986) observations of the inner southern spiral arm of M51 show that the tangential velocity component also behaves in a way which conforms with the density wave model. The molecular arms were compared with the H alpha ionized gas arms of Tully (1974) and it was found that the ionized gas appears to have its maximum intensity slightly outside the molecular arm

Transmon in a semi-infinite high-impedance transmission line: Appearance of cavity modes and Rabi oscillations

In this paper, we investigate the dynamics of a single superconducting artificial atom capacitively coupled to a transmission line with a characteristic impedance comparable to or larger than the quantum resistance. In this regime, microwaves are reflected from the atom also at frequencies far from the atom\u27s transition frequency. Adding a single mirror in the transmission line then creates cavity modes between the atom and the mirror. Investigating the spontaneous emission from the atom, we then find Rabi oscillations, where the energy oscillates between the atom and one of the cavity modes