On the Riemannian metric of α-entropies of density matrices

The Riemannian metric induced by quantum -entropies is proven to be monotone under stochastic mappings on the set of density matrices. The length of tangent vectors is essentially the Wigner-Yanase-Dyson skew information in this setting.Supported by the Hungarian National Foundation for Scientific Research, grant No. T-016924.     

Phonon density of states and phonon dispersion of superconducting MgB2

For the superconductor MgB2, we have calculated the phonon density of states （DOS）, phonon dispersion and Eliashberg function throughout the Brillouin zone （BZ）, using an empirical potential model. The calculated values are consistent with the theoretical and experimental values. The calculated results show our empiricalpotential model is available for MgB2.     

Phonon density of states and phonon dispersion of superconducting MgB2

For the superconductor MgB2, we have calculated the phonon density of states (DOS), phonon dispersion and Eliashberg function throughout the Brillouin zone (BZ), using an empirical potential model. The calculated values are consistent with the theoretical and experimental values. The calculated results show our empirical potential model is available for MgB2.     

Bounds on the density of states of random Schrödinger operators

Bounds are obtained on the unintegrated density of states ρ(E) of random Schrödinger operatorsH=?Δ + V acting onL ²(? ^d ) orl ²(? ^d ). In both cases the random potential is $$V: = \sum\limits_{y \in \mathbb{Z}^d } {V_y \chi (\Lambda (y))}$$ in which the \(\left\{ {V_y } \right\}_{y \in \mathbb{Z}^d }\) areIID random variables with densityf. The χ denotes indicator function, and in the continuum case the \(\left\{ {\Lambda (y)} \right\}_{y \in \mathbb{Z}^d }\) are cells of unit dimensions centered ony∈? ^d . In the finite-difference case Λ(y) denotes the sitey∈? ^d itself. Under the assumptionf ∈ L ₀ ^1+? (?) it is proven that in the finitedifference casep ∈ L ^∞(?), and that in thed= 1 continuum casep ∈ L _loc ^∞ (?).     

Partial disorder in itinerant antiferromagnets—electronic density of states

We examine the behaviour of magnetically disordered, strong correlated electron systems for the case of antiferromagnetic arrangements of the electron-spins. Preceding calculations in earlier papers for homogeneous systems yielded a state, where localized magnetic moments at the atomic sites were built up. The moments showed a partial homogeneous magnetic order in the so called mixed state. In this contribution we realize equivalent conditions for antiferromagnetism: After a coordinate transformation in an approximated Hubbard-Hamiltonian, it is possible to use a CPA-like method for statistical distributions of the vectoral localized moments in the same way as for homogeneous systems. As an example we study at first the quasi-particle density of states for a Lorentz-distribution of the moments.Work supported by the Deutsche Forschungsgemeinschaft     

Survival of charged ρ condensation at high temperature and density

The charged vector ρ mesons in the presence of external magnetic fields at finite temperature T and chemical potential μ have been investigated in the framework of the Nambu-Jona-Lasinio model.We compute the masses of charged ρ mesons numerically as a function of the magnetic field for different values of temperature and chemical potential.The self-energy of the ρ meson contains the quark-loop contribution,i.e.the leading order contribution in 1/N_C expansion.The charged ρ meson mass decreases with the magnetic field and drops to zero at a critical magnetic field eB_c,which indicates that the charged vector meson condensation,i.e.the electromagnetic superconductor can be induced above the critical magnetic field.Surprisingly,it is found that the charged ρ condensation can even survive at high temperature and density.At zero temperature,the critical magnetic field just increases slightly with the chemical potential,which indicates that charged ρ condensation might occur inside compact stars.At zero density,in the temperature range 0.2 — 0.5 GeV,the critical magnetic field for charged ρ condensation is in the range of 0.2 — 0.6 GeV~2,which indicates that a high temperature electromagnetic superconductor might be created at LHC.     

Surface rumpling of cubic CaTiO3 from density functional theory

In this paper, the structure of cubic CaTiO3 （001） surfaces with CaO and TiO2 terminations has been studied from density functional calculations. It has been found that the Ca atom has the largest relaxation for both kinds of terminations, and the rumpling of the CaO-terminated surface is much larger than that of TiO2-terminated surface. Also we have found that the metal atom relaxes much more prominently than the O atom does in each layer. The CaO-terminated surface is slightly more energetically favourahle than the TiO2-terminated surface from the analysis of the calculated surface energy.     

Band parameters of α-LiBeN semiconductor from density functional calculations

The structural, elastic, electronic, optical and thermal properties of α phase in LiBeN semiconductor have been studied using pseudo-potential plane wave method based on the density functional theory. The computed lattice parameter agrees well with previous theoretical work. The elastic constants and their pressure dependence are predicted using the static finite strain technique. A set of isotropic elastic parameters and related properties, namely bulk and shear moduli, Young’s modulus, Poisson’s ratio, average sound velocity and Debye temperature are numerically estimated in the frame work of the Voigt–Reuss–Hill approximation for α-LiBeN polycrystalline aggregate. The assignments of the structures in the optical spectra and band structure transitions have been examined and discussed. The thermal effect on heat capacities is investigated by the quasi-harmonic Debye model. To the best of our knowledge, most of the studied properties of the material of interest are reported for the first time.     

Electrostatic potential of several small molecules from density functional theory

A number of density functional theory (DFT) methods were used to calculate the electrostatic potential for the series of molecules N2, F2, NH3, H2O, CHF3, CHCl3, C6H6, TiF4, CO(NH2)2 and C4H5N3O compared with QCISD (quadratic configuration interaction method including single and double substitutions) results. Comparisons were made between the DFT computed results and the QCISD ab initio ones and MP2 ab initio ones, compared with the root-mean-square deviation and electrostatic potential difference contours figures. It was found that the hybrid DFT method B3LYP, yields electrostatic potential in good agreement with the QCISD results. It is suggest this is a useful approach, especially for large molecules that are difficult to study by ab initio methods.     

Tribological Properties of Polycarbonate Blended with High‐density Polyethylene and High‐density Polyethylene Grafted with Maleic Anhydride

High‐density polyethylene (HDPE) and maleic anhydride grafted HDPE (HDPE‐g‐MA) were selected as lubricant and compatibilizer, respectively, for improving the tribological and mechanical properties of polycarbonate (PC). The morphology of worn surfaces and debris was observed by means of scanning electron microscopy (SEM). The mated steel ring surface was analyzed by using SEM combined with energy dispersive spectroscopy (EDS). Both HDPE and HDPE‐g‐MA reduced the friction and wear of pure PC. HDPE‐g‐MA, which had a better compatibility with PC than HDPE, resulted in better improvement of the mechanical and tribological properties of the PC matrix. A 10 vol. % HDPE‐g‐MA reduced the wear of pure PC by 4 orders of magnitude, and the friction coefficient was reduced from 0.86 to 0.22. Such improvements in the tribological behavior resulted from the good self lubrication of HDPE and HDPE‐g‐MA. The PC/HDPE‐g‐MA (S_90‐0‐10) polyblend also showed higher notched impact strength than pure PC. It may be a useful material for application in tribological fields.     

Effects of discharge current and voltage on the high density of metastable helium atoms

Both hollow-cathode and Penning-type discharges were adopted to excite helium atoms to a metastable state. Experimental data indicate that Penning discharge is more suitable for generating high fractions of metastables in a low-density helium beam for laser-induced fluorescence technique in measuring electric fields at the edge of a plasma. The metastable density increases with increasing helium gas pressure in the range of 1.33×10^{-2}－66.7Pa. The highest metastable density of 3.8×10^{16}m^{-3} is observed at a static gas pressure of 66.7Pa. An approximately linear relationship between the density of metastable helium atoms and the plasma discharge current is observed. Magnetic field plays a very important role in producing a high density of metastable atoms in Penning discharge.     

Separability criteria based on Heisenberg–Weyl representation of density matrices

Separability is an important problem in theory of quantum entanglement. By using the Bloch representation of quantum states in terms of the Heisenberg–Weyl observable basis, we present a new separability criterion for bipartite quantum systems. It is shown that this criterion can be better than the previous ones in detecting entanglement. The results are generalized to multipartite quantum states.     

Stability of small Ni-Ti bimetallic clusters studied by density functional theory

The low-energy structures and the electronic and the magnetic properties of small NiNiNi$_{m}$Ti$_{n}$ clusters, lowest-energy structure, electronic and magnetic propertiesProject supported by the National Natural Science Foundation of China (Grant No.~10874039), and the Natural Science Foundation of Hebei Province of China (Grant Nos.~A2009000246 and 2009000243).3120A, 3640B, 2110K7/3/2009 12:00:00 AMThe low-energy structures and the electronic and the magnetic properties of small NiNiNi$_{m}$Ti$_{n}$ clusters, lowest-energy structure, electronic and magnetic propertiesProject supported by the National Natural Science Foundation of China (Grant No.~10874039), and the Natural Science Foundation of Hebei Province of China (Grant Nos.~A2009000246 and 2009000243).3120A, 3640B, 2110K7/3/2009 12:00:00 AMThe low-energy structures and the electronic and the magnetic properties of small Ni$_{n}$Ti$_{n}$ ($n=1$--$6$) and Ni$_{m}$Ti$_{n}$ ($1 \le n \le 4$, $1 \le m \le 4$, $n \ne m$) clusters are investigated by performing all-electron calculations based on density functional theory. Ground states and several isomers near the ground states are determined for these clusters. The results indicate that the growth of small Ni$_{m}$Ti$_{n}$ clusters prefers to form rich Ti--Ni and Ti--Ti bonds. When the percentage of titanium atoms is significantly greater than that of nickel atoms, the nickel atoms are most frequently found above the surface; in contrast, the titanium atoms prefer the bridging sites. A M\"{u}lliken spin population analysis indicates that the total spin of titanium-nickel clusters is not always zero.http://cpb.iphy.ac.cn/CN/10.1088/1674-1056/19/4/043102https://cpb.iphy.ac.cn/CN/article/downloadArticleFile.do?attachType=PDF&id=111644NimTin;clusters;lowest-energy;structure;electronic;and;magnetic;propertiesThe low-energy structures and the electronic and the magnetic properties of small Nin Tin(n = 1-6) and Ni m Ti n(1 ≤ n ≤ 4,1 ≤ m ≤ 4,n ≠ m) clusters are investigated by performing all-electron calculations based on density functional theory.Ground states and several isomers near the ground states are determined for these clusters.The results indicate that the growth of small Ni m Ti n clusters prefers to form rich Ti-Ni and Ti-Ti bonds.When the percentage of titanium atoms is significantly greater than that of nickel atoms,the nickel atoms are most frequently found above the surface;in contrast,the titanium atoms prefer the bridging sites.A Mu¨lliken spin population analysis indicates that the total spin of titanium-nickel clusters is not always zero.     

Effect of strain on charge density wave order in α-U

The effect of strain on charge density wave (CDW) order in $\alpha$-U is investigated within the framework of relativistic density-functional theory. The energetical stability of $\alpha$-U with CDW distortion is enhanced by the tensile strain along $a$ and $b$ axes, which is similar to the case of negative pressure and normal. However, the tensile strain along $c$ axis suppresses the energetical stability of CDW phase. This abnormal effect could be understood from the emergence of a new one-dimensional atomic chain along $c$ axis in $\alpha$-U. Furthermore, this effect is supported by the calculations of Fermi surface and phonon mode, in which the topological objects and the dynamical instability show opposite behaviors between strains along $a$/$b$ and $c$ axes.     

Demixing of amphiphile–polymer mixtures investigated using density functional theory

We construct a functional for amphiphile–polymer mixtures and investigate the demixing transition by using a proposed version of density functional theory. It is found that increase of the amphiphilic size ratio and polymer length can effectively promote phase separation of the systems. Phase diagrams are plotted to clarify these influences. The results provide an effective way of controlling the stability of the fluid–fluid phase equilibrium of the mixtures.     

Effects of various solar indices on accuracy of Earth’s thermospheric neutral density models

Four kinds of solar indices F10.7, E10.7, S10, Mg10 and four thermospheric neutral density models, i.e., CIRA72, DTM94, NRLMSISE00 and JB2006, are discussed. The CHAMP accelerometer data are used to calculate thermospheric total mass density. Based on the comparison of the model densities with CHAMP observations, the effects of various indices on the model accuracy are detected. It is found that under quiet and moderate solar conditions (F10.7<160), all of the models’ errors are reduced about 15% by using E...     

Calculation of the structure and IR spectrum of methyl-β-D-glucopyranoside by density functional theory

Structural-dynamic models of methyl-β-D-glucopyranoside have been constructed by a density functional method using a B3LYP functional in bases 6-31G(d) and 6-31+G(d,p). Energies have been minimized. Structures, dipole moments, polarizabilities, frequencies of normal modes in the harmonic approximation, and the intensity distribution in the molecular IR spectrum have been calculated. The calculation results have been compared with both the experimental spectra of methyl-β-D-glucopyranoside in the region 400–3700 cm^–1 and data obtained within the framework of an approach that uses the classical valence-force method to calculate normal mode frequencies and the quantum-chemical CNDO/2 technique to calculate the electronic structure.     

Energy density functional study of nuclear matrix elements for neutrinoless ββ decay

We present an extensive study of nuclear matrix elements (NME) for the neutrinoless double-beta decay of the nuclei 48Ca, 76Ge, 82Se, 96Zr, 100Mo, 116Cd, 124Sn, 128Te, 130Te, 136Xe, and 150Nd based on state-of-the-art energy density functional methods using the Gogny D1S functional. Beyond-mean-field effects are included within the generating coordinate method with particle number and angular momentum projection for both initial and final ground states. We obtain a rather constant value for the NMEs around 4.7 with the exception of 48Ca and 150Nd, where smaller values are found. We analyze the role of deformation and pairing in the evaluation of the NME and present detailed results for the decay of 150Nd.