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The effective hydrodynamic radius in the Stokes-Einstein relation is not a constant

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Communications in Theoretical Physics 2022年第9期74卷 177-182页

作者： gan ren School of Science Civil Aviation Flight University of ChinaGuanghan 618307China

Variants based on the assumption of effective hydrodynamic radius being a constant are usually adopted to test the Stokes-Einstein(SE)*** rationality of the assumption is examined by performing molecular dynamics simulations with the truncated Lennard-Jones-like(TLJ)model,Kob-Andersen model and ortho-terphenyl(OTP)*** results indicate the assumption is generally not established except for special *** effective hydrodynamic radius is observed to increase with decreasing temperature for TLJ model but is decreased for Kob-Andersen and OTP model;and which is almost a constant for TLJ particle with enough *** variant of SE relation D~Th is invalid for the three models except for the TLJ particle with enough *** propose similar inconsistency may be also existed in other liquids and the assumption should be critically evaluated when adopted to test the SE relation.

关键词： Stokes-Einstein relation effective hydrodynamic radius Stokes’formula

Supercooled liquids analogous fractional Stokes–Einstein relation in NaCl solution above room temperature

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Chinese Physics B 2019年第7期28卷 381-388页

作者： gan ren Shikai Tian Departments of Physics & Key Laboratory of Photonic and Optical Detection in Civil Aviation Civil Aviation Flight University of China

The Stokes–Einstein relation D^T/η and its two variants D~τ-1 and D^T/τ follow a fractional form in supercooled liquids, where D is the diffusion constant, T the temperature,η the shear viscosity, and τ the structural relaxation *** fractional Stokes–Einstein relation is proposed to result from the dynamic heterogeneity of supercooled *** this work, by performing molecular dynamics simulations, we show that the analogous fractional form also exists in sodium chloride(NaCl) solutions above room temperature.D~τ-1 takes a fractional form within 300–800 K;a crossover is observed in both D^T/τ and D^T/η.Both D^T/τ and D^T/η are valid below the crossover temperature Tx,but take a fractional form for T > *** results indicate that the fractional Stokes–Einstein relation not only exists in supercooled liquids but also exists in NaCl solutions at high enough temperatures far away from the glass transition *** propose that D^T/η and its two variants should be critically evaluated to test the validity of the Stokes–Einstein relation.

关键词： sodium chloride solutions supercooled liquids molecular dynamics Stokes–Einstein relation

Fractional Stokes–Einstein relation in TIP5P water at high temperatures

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Chinese Physics B 2018年第6期27卷 307-314页

作者： gan ren Ge Sang Science and Technology on Surface Physics and Chemistry Laboratory Jiangyou 621908 China

Fractional Stokes–Einstein relation described by D ～（τ/T）~ξ is observed in supercooled water, where D is the diffusion constant, τ the structural relaxation time, T the temperature, and the exponent ξ =τ^（-1）. In this work, the Stokes–Einstein relation in TIP5 P water is examined at high temperatures within 400 K–800 K. Our results indicate that the fractional Stokes–Einstein relation is explicitly existent in TIP5P water at high temperatures, demonstrated by the two usually adopted variants of the Stokes–Einstein relation, D ～τ^（-1）τand D ～ T/τ, as well as by D ～ T/η, where η is the shear viscosity. Both D ～τ^（-1）τand D ～ T/τ are crossed at temperature Tx= 510 K. The D ～τ^（-1）τis in a fractional form as D ～ τ ξwith ξ =-2.09 for T ≤ Txand otherwise ξ =τ^（-1）.25. The D ～ T/τ is valid with ξ =τ^（-1）.01 for T ≤ Txbut in a fractional form for T Tx. The Stokes–Einstein relation D ～ T/η is satisfied below Tx = 620 K but in a fractional form above Tx. We propose that the breakdown of D ～ T/η may result from the system entering into the super critical region, the fractional forms of D ～τ^（-1）τand D ～ T/τ are due to the disruption of the hydration shell and the local tetrahedral structure as well as the increase of the shear viscosity.

关键词： Stokes-Einstein relation TIP5P water molecular dynamics hydration shells

Fractional variant of Stokes–Einstein relation in aqueous ionic solutions under external static electric fields

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Chinese Physics B 2020年第3期29卷 323-329页

作者： gan ren Shikai Tian Departments of Physics&Key Laboratory of Photonic and Optical Detection in Civil Aviation Civil Aviation Flight University of ChinaGuanghan 618307China

Both ionic solutions under an external applied static electric field E and glassy-forming liquids under undercooled state are in non-equilibrium *** this work,molecular dynamics(MD)simulations with three aqueous alkali ion chloride(NaCl,KCl,and RbCl)ionic solutions are performed to exploit whether the glass-forming liquid analogous fractional variant of the Stokes–Einstein relation also exists in ionic solutions under *** results indicate that the diffusion constant decouples from the structural relaxation time under E,and a fractional variant of the Stokes–Einstein relation is observed as well as a crossover analogous to the glass-forming liquids under *** fractional variant of the Stokes–Einstein relation is attributed to the E introduced deviations from Gaussian and the nonlinear effect.

关键词： ionic solutions Stokes–Einstein relation non-equilibrium steady state molecular dynamics simulation

The Stokes-Einstein-Debye relation in ortho-terphenyl liquid

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Communications in Theoretical Physics 2024年第5期76卷 148-153页

作者：任淦 School of Science Civil Aviation Flight University of ChinaGuanghan 618307China

The Stokes–Einstein–Debye(SED)relation is proposed to be broken down in supercooled liquids by many ***,conclusions are usually drawn by testing some variants of the SED relation rather than its original *** this work,the rationality of the SED relation and its variants is examined by performing molecular dynamics simulations with the Lewis–Wahnstrom model of ortho-terphenyl(OTP).The results indicate the original SED relation is valid for OTP but the three variants are all broken *** inconsistency between the SED relation and its variants is analyzed from the heterogeneous dynamics,the adopted assumptions and approximations as well as the interactions among ***,care should be taken when employing the variants to judge the validity of the SED relation in supercooled liquids.

关键词： Stokes-Einstein-Debye relation Stokes-Einstein relation supercooled liquids Stokes'formula

Phase-and spin-dependent manipulation of leakage of Majorana mode into double quantum dot

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Chinese Physics B 2021年第7期30卷 636-640页

作者： Fu-Bin Yang gan ren Lin-Guo Xie Department of Physics and Key Laboratory of Photonic and Optical Detection in Civil Aviation Civil Aviation Flight University of ChinaGuanghan 618307China

We present a phase-and spin-dependent manipulation of leakage of a Majorana mode into a double quantum *** study the density of states(DOS)to show the effect of phase change factor on the Majorana leakage into(out)of a double quantum *** DOS is derived from the Green's function of the quantum dot by the equation of motion method,and exhibits a formant structure whenφ=0,2πand a resonance shape whenφ=0.5πand 1.5π.Also,it changes more strongly under the spin-polarized coefficient than the non-polarized *** a theoretical model can be modified to explore the spin-dependent effect in the hybrid Majorana quantum dot system.

关键词： spin-dependent coupling Majorana bound states double quantum dots

Supersymmetric Electroweak Corrections to the Decay of the Heavy Chargino into the Light Chargino and Z Boson

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Communications in Theoretical Physics 2002年第8期38卷 173-180页

作者： ZHOU Pei-Jun MA Wen-gan ZHANG ren-You WAN Lang-Hui Department of Modern Physics University of Science and Technology of China Hefei 230027 China Department of Modern Physics University of Science and Technology of China Hefei 230027 China Department of Modern Physics University of Science and Technology of China Hefei 230027 China Department of Modern Physics University of Science and Technology of China Hefei 230027 China

The supersymmetric electroweak corrections to the partial width of the decay x2+ → Z0x1-+, including thecontributions from the third generation quarks and squarks, are presented within the minimal supersymmetric standardmodel. With the reasonable parameters sets, which open this decay channel kinematically, the relative corrections canreach the value of ～ -6%. Therefore they should be taken into consideration for the precise experimental measurementat future colliders.

关键词： minimal supersymmetric standard model, chargino, electroweak correction

eμ Production in R-Parity Violating Supersymmetric Model at Hadron Colliders

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Communications in Theoretical Physics 2007年第3X期48卷 491-501页

作者： WANG Shao-Ming HAN Liang MA Wen-gan ZHANG ren-You JIANG Yi Department of Modern Physics University of Science and Technology of China Hefei 230026 China

We investigate the lepton flavor violating productions pp/pp→eμ ＋ X in the framework of the R-parity violating （RPV） supersymmetric model at the Tevatron and the CERN large hadron collider （LHC）. We present the total cross sections including the next-to-leading order （NLO） QCD corrections and the contribution from gluon-gluon fusion subprocess. Our numerical results show that the one-loop QCD corrections significantly increase the tree-level cross sections, and the variation of K factor is in the range between 1.28 （1.32） and 1.79 （1.58） at the Tevatron （LHC）. We find that the QCD correction from the one-loop gluon-gluon fusion subprocess is remarkable at the LHC and should be taken into account.

关键词： R-parity violating supersymmetric model QCD corrections

Analysis on Initial Defects Based on Mechanical State of Meniscus Shell

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Journal of Iron and Steel Research International 2015年第12期22卷 1085-1090页

作者： Xiang-ning MENG ren-gan LIN Jie YANG Xiao-jing ZUO Miao-yong ZHU School of Materials and Metallurgy Northeastern University

The meniscus shell plays an important role in slab quality and process operation for continuously cast steel. One decisive reason is initial solidifying shell and growing dendrite under the mechanical stress caused by mold oscil- lation and liquid steel flow to generate disturbance of casting. The mechanical state of meniscus shell was analyzed using mathematical models in combination with thermo-physical properties and flow rate of steel to shed light on the formation of initial defects. The results show that the mold oscillation is a critical factor on the initial crack formation because the periodic stress makes the shell bending. The formed crack may also expand and propagate due to the fol- lowing secondary cooling and straightening behavior. The primary dendrite has high possibility to be broken by fluid flow in the solidification front to lead to the non-uniform thickness of solidifying shell. The inter-dendrite bridging is also likely to be formed to produce other internal defects, such as air hole and solute enrichment in the residual mol- ten steel located in the bridging area.

关键词： continuous casting mold oscillationl meniscus shell initial defect mathematical model