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941.
The electronic band structure and magnetic properties of iron phthalocyanine (FePc) monolayer were investigated by using the first-principles all-electron full-potential linearized augmented plane wave energy band method. It is found that the ferromagnetic FePc monolayer is energetically more stable than the paramagnetic one. The exchange interaction, which splits the majority and minority bands, influences strongly on the electronic structure near the Fermi level (EF). Magnetic moment of the central Fe atom is calculated to 1.95 μB. The range of the positive polarization of Fe site is larger in the out-of-plane than in the in-plane direction. The FePc ligand remains paramagnetic. The presence of states at EF indicates the metallic character of FePc monolayer both for the paramagnetic and ferromagnetic states. However, the large density of states at EF of the majority spins in the ferromagnetic state is expected to cause a phase transition to insulating antiferromagnetic state from the metallic ferromagnetic one. 相似文献
942.
Svetlana V. Kirpichenko Bagrat A. Shainyan Erich Kleinpeter 《Journal of Physical Organic Chemistry》2012,25(12):1321-1327
The conformational analysis of the first representative of the Si‐alkoxy substituted six‐membered Si,N‐heterocycles, 1,3‐dimethyl‐3‐isopropoxy‐3‐silapiperidine, was performed by low‐temperature 1H and 13C NMR spectroscopy and DFT theoretical calculations. In contrast to the expectations from the conformational energies of methyl and alkoxy substituents, the Meaxi‐PrOeq conformer was found to predominate in the conformational equilibrium in the ratio Meaxi‐PrOeq : Meeqi‐PrOax of ca. 2 : 1 as from the 1H and 13C NMR study. The thermodynamic parameters obtained by the complete line shape analysis showed that the main contribution to the barrier to ring inversion originates from the entropy term of the free energy of activation. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
943.
V.A. Ryzhov A.V. Lazuta P.L. Molkanov V.P. Khavronin A.I. Kurbakov V.V. Runov Ya.M. Mukovskii A.E. Pestun R.V. Privezentsev 《Journal of magnetism and magnetic materials》2012
The magnetic, transport and structural properties are studied for La0.83Sr0.17MnO3 and La0.82Sr0.18CoO3 single crystals with nearly the same doping and the metallic ground state. Their comparisons have shown that ferromagnetic clusters originate in the paramagnetic matrix below Т?>TC in both samples and exhibit similar properties. This suggests the possible universality of such phenomena in doped mixed-valence oxides of transition metals with the perovskite-type structure. The cluster density increases on cooling and plays an important role on the physical properties of these systems. The differences in cluster evolutions and scenarios of their insulator–metal transitions are related to different magnetic behaviors of the matrixes in these crystals that is mainly due to distinct spin states of the Mn3+ and Co3+ ions. 相似文献
944.
We calculate three-loop corrections to correlation functions of heavy-quark currents in the low- and high-energy regions. We present 30 coefficients both in the low-energy and the high-energy expansion of the scalar and the vector correlator with non-diagonal flavour structure. In addition we compute 30 coefficients in the high-energy expansion of the diagonal vector, axial-vector, scalar and pseudo-scalar correlators. Possible applications of our new results are improvements of lattice-based quark-mass determinations and the approximate reconstruction of the full momentum dependence of the correlators. 相似文献
945.
使用基于密度泛函理论的第一性原理平面波赝势法,研究了Nb原子链的结构稳定性和电子结构性质.计算表明,Nb原子可以形成线性链,平面之字形,二聚化以及梯子形等一系列的一 维链式结构.结果也显示,其中之字形结构最为稳定,其他结构均为亚稳的.通过第一性原理 计算的电子结构和Jahn-Teller效应,讨论了这些结构的相对稳定性以及各链式结构的电子 能带、态密度和电荷密度等性质.
关键词:
Nb原子链
结构稳定性
电子结构
从头计算 相似文献
946.
Michel Pierre Takashi Suzuki Haruki Umakoshi 《Journal of Applied Analysis & Computation》2018,8(3):836-858
We consider the asymptotic behavior for large time of solutions to reaction-diffusion systems modeling reversible chemical reactions. We focus on the case where multiple equilibria exist. In this case, due to the existence of so-called "boundary equilibria", the analysis of the asymptotic behavior is not obvious. The solution is understood in a weak sense as a limit of adequate approximate solutions. We prove that this solution converges in L^1 toward an equilibrium as time goes to infinity and that the convergence is exponential if the limit is strictly positive. 相似文献
947.
Khang Hoang 《固体物理学:研究快报》2016,10(12):915-918
Erbium (Er) doped GaN has been studied extensively for optoelectronic applications, yet its defect physics is still not well understood. In this work, we report a first‐principles hybrid density functional study of the structure, energetics, and thermodynamic transition levels of Er‐related defect complexes in GaN. We discover for the first time that ErGa–CN–VN, a defect complex of Er, a C impurity, and an N vacancy, and ErGa–ON–VN, a complex of Er, an O impurity, and an N vacancy, form defect levels at 0.18 eV and 0.46 eV below the conduction band, respectively. Together with ErGa–VN, a complex of Er and an N vacancy which has recently been found to produce a donor level at 0.61 eV, these defect complexes provide explanation for the Er‐related defect levels observed in experiments. The role of these defects in optical excitation of the luminescent Er center is also discussed. 相似文献
948.
Julio Becerra Guerrero Fernando Rambla-Barreno 《Journal of Mathematical Analysis and Applications》2009,360(1):254-264
We prove that for every member X in the class of real or complex JB*-triples or preduals of JBW*-triples, the following assertions are equivalent:
- (1) X has the fixed point property.
- (2) X has the super fixed point property.
- (3) X has normal structure.
- (4) X has uniform normal structure.
- (5) The Banach space of X is reflexive.
Keywords: JB*-triple; Fixed point; Normal structure 相似文献
949.
Karina Muñoz-Becerra Nery Villegas-Escobar César Zúñiga-Loyola Diego Cortés-Arriagada 《Molecular physics》2019,117(9-12):1451-1458
ABSTRACTAurones are potential candidates to be employed as fluorescent probes or as pharmacophores for biological applications. This work describes a density functional theory (DFT) and time-dependent -DFT study at the PBE0/6-31?+?G(d) level of theory to analyse the structural, electronic and photophysical properties of a series of new proposed 4′-amine-aurone derivatives in its E and Z isomeric conformations. The maximum absorption wavelength of the proposed aurones appears in the range 390???514?nm, while the most allowed emission pathways were computed in the range 493–530?nm. The bathochromic shift of these compounds with respect to the non-substituted aurone is modulated by the acceptor strength of the added 4-substituents, in addition to the ability of the substituents to localise the frontier molecular orbitals over the acceptor benzofuranone moiety without losing the tricyclic planarity, which favours the push–pull nature of these molecules. The influence of the 4-substituent is also evidenced in the Stokes shifts for the whole series; as the electron-withdrawing character of the 4-substituents enhances, higher is the polarisation of the structure resulting in higher Stokes shifts. As a result, -CF3 and -NO2 substituents were responsible of larger Stokes shifts, then compounds containing these substituents are proposed as potential fluorescence probes for useful applications in biological systems. 相似文献
950.
Quantum mechanical uncertainty relations are fundamental consequences of the incompatible nature of noncommuting observables. In terms of the coherence measure based on the Wigner-Yanase skew information, we establish several uncertainty relations for coherence with respect to von Neumann measurements, mutually unbiased bases(MUBs), and general symmetric informationally complete positive operator valued measurements(SIC-POVMs),respectively. Since coherence is intimately connected with quantum uncertainties, the obtained uncertainty relations are of intrinsically quantum nature, in contrast to the conventional uncertainty relations expressed in terms of variance,which are of hybrid nature(mixing both classical and quantum uncertainties). From a dual viewpoint, we also derive some uncertainty relations for coherence of quantum states with respect to a fixed measurement. In particular, it is shown that if the density operators representing the quantum states do not commute, then there is no measurement(reference basis) such that the coherence of these states can be simultaneously small. 相似文献