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Yong Wang

Publications and source records attributed to Yong Wang.

At least 685 records · Page 38Linked to original sources
arXiv2011

Time-dependent versus static quantum transport simulations beyond linear response

To explore whether the density-functional theory non-equilibrium Green's function formalism (DFT-NEGF) provides a rigorous framework for quantum transport, we carried out time-dependent density functional theory (TDDFT) calculations of the transient current through two realistic molecular devices, a carbon chain and a benzenediol molecule inbetween two aluminum electrodes. The TDDFT simulations for the steady state current exactly reproduce the results of fully self-consistent DFT-NEGF calculations even beyond linear response. In contrast, sizable differences are found with respect to an equilibrium, non-self-consistent treatment which are related here to differences in the Kohn-Sham and fully interacting susceptibility of the device region. Moreover, earlier analytical conjectures on the equivalence of static and time-dependent approaches in the low bias regime are confirmed with high numerical precision.

cond-mat.mtrl-sci↗
arXiv2010

Vanishing Viscosity Limit for Isentropic Navier-Stokes Equations with Density-dependent Viscosity

In this paper, we study the vanishing viscosity limit of one-dimensional isentropic compressible Navier-Stokes equations with density-dependent viscosity, to the isentropic compressible Euler equations. Based on several new uniform estimates to the viscous systems, in addition to the framework recently established by G. Chen and M. Perepelitsa, we justify that the finite energy solution of the isentropic compressible Euler equations for a large class of initial data can be obtained as the inviscid limit of the compressible Navier-Stokes equations even when the viscosity depends on the density.

math.AP↗
arXiv2009

Equivariant heat invariants of the Laplacian and nonmininmal operators on differential forms

In this paper, we compute the first two equivariant heat kernel coefficients of the Bochner Laplacian on differential forms. The first two equivariant heat kernel coefficients of the Bochner Laplacian with torsion are also given. We also study the equivariant heat kernel coefficients of nonmininmal operators on differential forms and get the equivariant Gilkey-Branson-Fulling formula.

math.DG↗
arXiv2009

Prediction of a spin-polarized two-dimensional electron gas at the LaAlO3/EuO(001) interface

First-principles calculations predict the existence of a spin-polarized two-dimensional electron gas (2DEG) at the LaO/EuO interface in a LaAlO3/EuO (001) heterostructure. This polar interface favors electron doping into the Eu-5d conduction bands resulting in a 2DEG formed at the interface. Due to the exchange splitting of the Eu-5d states the 2DEG is spin-polarized below the Curie temperature of EuO. The predicted mechanism for the formation of a spinpolarized 2DEG at the interface between polar and ferromagnetic insulators may provide a robust magnetism of the 2DEG which is interesting for spintronics applications.

cond-mat.mtrl-sci↗
arXiv2008

A general type of twisted anomaly cancellation formulas

For even dimensional manifolds, we prove some twisted anomaly cancellation formulas which generalize some well-known cancellation formulas. For odd dimensional manifolds, we obtain some modularly invariant characteristic forms by the Chern-Simons transgression and we also get some twisted anomaly cancellation formulas.

math.DG↗
arXiv2007

Derivations of Normalized Mutual Information in Binary Classifications

This correspondence studies the basic problem of classifications - how to evaluate different classifiers. Although the conventional performance indexes, such as accuracy, are commonly used in classifier selection or evaluation, information-based criteria, such as mutual information, are becoming popular in feature/model selections. In this work, we propose to assess classifiers in terms of normalized mutual information (NI), which is novel and well defined in a compact range for classifier evaluation. We derive close-form relations of normalized mutual information with respect to accuracy, precision, and recall in binary classifications. By exploring the relations among them, we reveal that NI is actually a set of nonlinear functions, with a concordant power-exponent form, to each performance index. The relations can also be expressed with respect to precision and recall, or to false alarm and hitting rate (recall).

cs.LG↗
arXiv2007

Time reversal Aharonov-Casher effect in mesoscopic rings with Rashba spin-orbital interaction

The time reversal Aharonov-Casher (AC) interference effect in the mesoscopic ring structures, based on the experiment in Phys. Rev. Lett. \textbf{97}, 196803 (2006), is studied theoretically. The transmission curves are calculated from the scattering matrix formalism, and the time reversal AC interference frequency is singled out from the Fourier spectra in numerical simulations. This frequency is in good agreement with analytical result. It is also shown that in the absent of magnetic field, the Altshuler-Aronov-Spivak type (time reversal) AC interference retains under the influence of strong disorder, while the Aharonov-Bohm type AC interference is suppressed.

cond-mat.mes-hall↗
arXiv2007

Unitarity Constraints on effective interaction in $πN$ scattering

Positivity constraints are derived on pion-nucleon scattering amplitudes and their even-order derivatives inside the Mandelstam Triangle with the help of dispersion relations. Fairly interesting constraints are obtained on some of the low energy constants, by a combination of the chiral perturbation theory for heavy baryons and existing fitting results from available pion-nucleon phase shifts at intermediate energies.

hep-ph↗
arXiv2006

Chern-Connes Character for the Invariant Dirac Operator in Odd Dimensions

In this paper we give a proof of the Lefschetz fixed point formula of Freed$^{\rm [1]}$ for an orientation-reversing involution on an odd dimensional spin manifold by using the direct geometric method introduced in [2] and then we generalize this formula under the noncommutative geometry framework.

math.DG↗
arXiv2006

Gravity and the Noncommutative Residue for Manifolds with Boundary

We prove a Kastler-Kalau-Walze type theorem for the Dirac operator and the signature operator for $3,4$-dimensional manifolds with boundary. As a corollary, we give two kinds of operator theoretic explanations of the gravitational action in the case of 4-dimensional manifolds with flat boundary.

math.DG↗
arXiv2006

Differential Forms and the Wodzicki Residue for Manifolds with Boundary

In [3], Connes found a conformal invariant using Wodzicki's 1-density and computed it in the case of 4-dimensional manifold without boundary. In [14], Ugalde generalized the Connes' result to $n$-dimensional manifold without boundary. In this paper, we generalize the results of [3] and [14] to the case of manifolds with boundary.

math.DG↗
arXiv2005

Consistency in Formulation of Spin Current and Torque Associated with a Variance of Angular Momentum

Stimulated generally by recent interest in the novel spin Hall effect, the nonrelativistic quantum mechanical conserved currents, taken into account of spin-orbit coupling, are rigorously formulated based on the symmetries of system and Noether' theorem. The quantum mechanical force on the spin as well as the torque associated with the variance of angular momentum are obtained. Consequently, the kinetic interpretation of the variances of spin and orbit angular momentum currents implies a torque on the "electric dipole" associated with the moving spin. The bearing of the force and the torque on the properties of spin current in a two-dimensional electron gas with the Rashba spin-orbit interaction is discussed.

cond-mat.mes-hall↗
arXiv1996

Mixed-state penetration depths in s-wave and d-wave superconductors

We report on a microscopic calculation of the current and magnetic field distribution in the mixed state of model s-wave and d-wave superconductors. For the d-wave case, we find that corrections to London theory are important at fields small compared to $H_{c2}$. The field distribution is influenced by both superfluid-velocity dependence and non-locality in the current response function of the mixed state. We compare our calculations with recent muon spin rotation measurements in high temperature superconductors.

cond-mat↗