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Density functional theory study on the structural and electronic properties of Ag-adsorbed (MgO)_n clusters

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Science china(physics,Mechanics & Astronomy) 2009年第5期52卷 734-741页

作者： GE GuiXian1, JING Qun1 & LUO YouHua2,3 1 Key Laboratory of Ecophysics and Department of physics, Normal College, Shihezi university, Shihezi 832003, china 2 school of Science, East china university of Science and Technology, Shanghai 200237, china 3 institute for theoretical physics, henan university, kaifeng 475004, china Key Laboratory of Ecophysics and Department of physics Normal College Shihezi University Shihezi China school of Science East China University of Science and Technology Shanghai China institute for theoretical physics Henan University Kaifeng China

Equilibrium geometries, charge distributions, stabilities and electronic properties of the Ag-adsorbed (MgO)n (n = 1-8) clusters have been investigated by density functional theory (DFT) with generalized gradient approximation (GGA) for exchange-correlation functional. The results show that hollow site is energetically preferred for n≥4, and the incoming Ag atoms tend to cluster on the existing Ag cluster. The Mulliken populations indicate that the interaction between the Ag atom and Magnesia clusters is mainly induced by a weak atomic polarization. The adsorbed Ag atom only causes charge redistributions of the atoms near itself. The effect of the adsorbed Ag atom on the bonding natures and structural features of Magnesia clusters is minor. Furthermore, the investigations on the first energy difference, fragmentation energies and electron affinities show that the Ag(MgO)4 and Ag(MgO)6 are the most stable among studied clusters.

关键词： Ag (MgO)_n clusters geometries electronic properties

Light A physics in the lepton-specific two-Higgs doublet model

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Science china(physics,Mechanics & Astronomy) 2010年第11期53卷 1981-1987页

作者： CAO JunJie 1,HENG ZhaoXia 2,3 & WAN PeiHua 1 1 College of physics & information Engineering,henan Normal university,Xinxiang 453007,china 2 Key Laboratory of Frontiers in theoretical physics,institute of theoretical physics,Chinese Academy of Sciences,Beijing 100190,china 3 Kavli institute for theoretical physics china,Chinese Academy of Sciences,Beijing 100190,china College of physics & information Engineering Henan Normal University Xinxiang China Key Laboratory of Frontiers in theoretical physics Institute of Theoretical Physics Chinese Academy of Sciences Beijing China Kavli institute for theoretical physics china Chinese Academy of Sciences Beijing China

We examine various direct and indirect constraints on the lepton-specific two-Higgs doublet model and discuss its phenomenology at colliders in the allowed parameter *** constraints we consider come from the precision electroweak data,the direct search for Higgs boson,the muon anomalous magnetic moment,as well as some theoretical consistency *** find that in the allowed parameter space the CP-odd Higgs boson A is rather light (m A 30 GeV with 95% possibility),which is composed dominantly by the leptonic Higgs and decays dominantly into τ + τ;while the SM-like Higgs boson h (responsible largely for electroweak symmetry breaking) decays dominantly in the mode h → AA → 4τ with a large decay width,which will make the Higgs discovery more difficult at the ***,this scenario predicts rare Z decays Z → AAA and Z →τ + τA with their branching ratios ranging from 10-8 to 10-and 10-5 to 10-4 respectively,which may be accessible at the GigaZ option of the ILC.

关键词： Lepton-specific two-Higgs doublt model light Higgs boson A Z decays

Surface-induced interaction of colloidal particles in isotropic liquid crystals

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Communications in theoretical physics 2024年第7期76卷 114-122页

作者： Hualing Zhang kaifeng Weng Rui Ma Department of physics College of Physical Science and TechnologyXiamen UniversityXiamen 361005China Fujian Provincial Key Laboratory for Soft Functional Materials Research Research Institute for Biomimetics and Soft MatterXiamen UniversityXiamen 361005China

In this work,we study the interaction between two colloidal particles in a liquid crystal that is in the isotropic *** interaction is caused by surface-induced polarization of the liquid crystal molecules in the vicinity of the *** find that the interaction is short-ranged in both 2D and 3D *** symmetric homeotropic anchoring conditions,the interaction is *** under anti-symmetric homeotropic anchoring conditions,the interaction is repulsive at short distances but attractive at intermediate *** particle size has a strong impact on the effective interaction force.

关键词： surface-induced interaction colloidal particles liquid crystals

Ultrafast excitation relaxation in light-harvesting complex LH2 from *** 601

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Science china Chemistry 2004年第3期47卷 192-199页

作者： GUO Lijun1,2, LIU Yuan3, LIU Weimin2, GUO Junhua1, XU Chunhe3 & QIAN Shixiong2 1. school of physics and information optoelectronics, henan university, kaifeng 475001, china 2. physics Department, Fudan university, Shanghai 200433, china 3. Shanghai institute of Plant Physiology, Chinese Academy of Sciences, Shanghai 200032, china school of physics and information optoelectronics Henan University Kaifeng China physics Department Fudan University Shanghai China Shanghai institute of Plant Physiology Chinese Academy of Sciences Shanghai China

The energy relaxation and kinetic evolution of transient spectra of bacteriochloro- phylls (BChls) in light-harvesting complex LH2 from Rb. sphaeroides 601 were investigated using femtosecond pump-probe technique. Upon 783 nm excitation, the energy at B800 BChls ex-periences an intramolecular redistribution with 0.35 ps time constant before transferring to B850 BChls. With tuning the excitation wavelength, the dynamical evolution of excited BChls was clearly observed, which indicates an obvious competition between the ground state bleaching and excited state absorption (ESA) of BChls involved and an isosbestic point near 818 nm, and also demonstrates that from the lower electronic excited state of B800 BChls to the higher exci-tonic state of B850 BChls is an efficient routine for energy transfer. The excitation energy in higher excitonic states of B850 BChls relaxes rapidly to the next lowest excitonic state by inter-conversion, delocalization to adjacent molecular, populating the lowest excitonic state and the change of molecular conformation.

关键词： photosynthesis, light-harvesting complex, energy transfer, ultrafast, dynamics, purple bacteria.

The information entropy of a static dilaton black hole

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Science china(physics,Mechanics & Astronomy) 2008年第2期51卷 113-125页

作者： LIU ChengZhou institute of theoretical physics, Binzhou university, Binzhou 256600, china Department of physics, Beijing Normal university, Beijing 100875, china institute of theoretical physics Binzhou University Binzhou China Department of physics Beijing Normal University Beijing China

In accordance with holographic principle, by calculating the statistical entropy of the quantum field just at the event horizon of the Garfinkle-Horowitz-Strominger dilaton black hole, the information entropy of the black hole was investigated and the Bekenstein-Hawking formula was obtained. The results show that black hole entropy is identical with the statistical entropy of the quantum field at the horizon. Using the generalized uncertainty relation, the divergence of the state density near the event horizon in usual quantum field theory was removed, and the cutoffs and the little mass approximation in the heat gas method of black hole entropy were avoided. Thus, the microstates of the massive scalar field just at the event horizon of the static dilaton black hole were studied directly and a description on holograph principle was presented. By using residue theorem, the integral difficulty in the calculation was overcome, and the information entropy and the Bekenstein-Hawking formula were obtained quantitatively. Compared with the black hole entropy from the loop quantum gravity, the consistency of methods and results of calculating black hole entropy in non-commutative quantum field theory and loop quantum gravity was investigated. By this, the gravity correction constant in the generalized uncertainty relation was suggested and the sense of holographic principle was discussed.

关键词： black hole entropy holographic principle non-commutative quantum field theory event horizon loop quantum gravity

Constraints of f(R) gravity in Palatini approach with observational Hubble data

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Science china(physics,Mechanics & Astronomy) 2011年第8期54卷 1378-1383页

作者： ZHAI ZhongXu & LIU WenBiao Department of physics, institute of theoretical physics, Beijing Normal university, Beijing 100875, china Department of physics Institute of Theoretical Physics Beijing Normal University Beijing China

We use the newly released observational H(z) data (OHD), the Cosmic Microwave Background (CMB) shift parameter, and the Baryon Acoustic Oscillation (BAO) measurements data to constrain cosmological parameters of f(R) gravity in Palatini formalism in which the f(R) form is defined as f(R) = R β/Rn. Under the assumption of a spatially flat FRW universe, we get the best fitting results of the free parameters (Ωm0, n). In the calculation, we marginalize the likelihood function over H0 by integrating the probability density P ∝ e-χ2/2 to obtain the best fitting results and the confidence regions in the Ωm0-n plane. The constraints results of (Ωm0, n) = (0.33, 0.41) by OHD only and (Ωm0, n) = (0.23, 0.08) by the combination of OHD+CMB+BAO both indicate that the universe goes through three last phases, i.e., radiation dominated, matter-dominated, and late time accelerated expansion without introduction of dark energy.

关键词： f(R) gravity OHD CMB BAO accelerating expansion dark energy

Lepton flavor violating Z-boson decays at GigaZ as a probe of supersymmetry

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Science china(physics,Mechanics & Astronomy) 2010年第11期53卷 1949-1952页

作者： YANG JinMin 1,2 1 Department of physics,henan Normal university,Xinxiang 453007,china 2 institute of theoretical physics,Chinese Academy of Sciences,Beijing 100190,china Department of physics Henan Normal University Xinxiang China institute of theoretical physics Chinese Academy of Sciences Beijing China

This paper briefly reviews the lepton flavor violating Z-decays at GigaZ as a probe of supersymmetry by focusing on Z → i j in two representative supersymmetric models: the minimal supersymmetric model without R-parity and the supersymmetric seesaw *** work concludes that under the current experimental constraints from LEP and i → j γ,these rare decays can still be enhanced to reach the sensitivity of the ***,supersymmetry can be probed via these decays at GigaZ.

关键词： Z-decay GigaZ supersymmetry

Lookback time as a test for f(R) gravity in the Palatini approach

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Research in Astronomy and Astrophysics 2011年第11期11卷 1257-1265页

作者： Zhong-Xu Zhai and Wen-Biao Liu Department of physics, institute of theoretical physics, Beijing Normal university, Beijing 100875, china Department of physics Institute of Theoretical Physics Beijing Normal University Beijing 100875 China

We use the recently released data of lookback time (LT)-redshift relation, the cosmic microwave background shift parameter and the baryon acoustic oscillation measurements to constrain cosmological parameters of f (R) gravity in the Palatini formalism by considering the f (R) form of type (a) f (R) = R β/Rn and (b) f (R) = R + α ln R β. Under the assumption of a Friedmann-Robertson-Walker universe, we achieved the best fitting results of the free parameters (Ωm0, n) for (a) and (Ωm0, α) for (b). We find that current LT data can provide interesting and effective constraints on gravity models. Compared with other data, the LT constraints favor a smaller value of the non-relativistic matter energy density.

关键词： cosmology cosmic microwave background

Comparison of dark energy models:A perspective from the latest observational data

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中国科学：物理学、力学、天文学英文版 2010年第9期53卷 1631-1645页

作者： LI Miao1,2,LI XiaoDong2,3 & ZHANG Xin1,4 1Kavli institute for theoretical physics china,Chinese Academy of Sciences,Beijing 100190,china 2Key Laboratory of Frontiers in theoretical physics,institute of theoretical physics,Chinese Academy of Sciences,Beijing 100190,china 3Interdisciplinary Center for theoretical Study,university of Science and Technology of china,Hefei 230026,china 4Department of physics,College of Sciences,Northeastern university,Shenyang 110004,china Kavli institute for theoretical physics china Chinese Academy of Sciences Beijing China Key Laboratory of Frontiers in theoretical physics Institute of Theoretical Physics Chinese Academy of Sciences Beijing China Interdisciplinary Center for theoretical Study University of Science and Technology of China Hefei China Department of physics College of Sciences Northeastern University Shenyang China

We compare some popular dark energy models under the assumption of a flat universe by using the latest observational data including the type Ia supernovae Constitution compilation,the baryon acoustic oscillation measurement from the Sloan Digital Sky Survey,the cosmic microwave background measurement given by the seven-year Wilkinson Microwave Anisotropy Probe observations and the determination of H0 from the Hubble Space *** comparison statistics such as the Bayesian and Akaike information criteria are applied to assess the worth of the *** statistics favor models that give a good fit with fewer *** on this analysis,we find that the simplest cosmological constant model that has only one free parameter is still preferred by the current *** other dynamical dark energy models,we find that some of them,such as the αdark energy,constant w,generalized Chaplygin gas,Chevalliear-Polarski-Linder parametrization,and holographic dark energy models,can provide good fits to the current data,and three of them,namely,the Ricci dark energy,agegraphic dark energy,and Dvali-Gabadadze-Porrati models,are clearly disfavored by the data.

关键词： dark energy models observational constraints model comparison information criteria