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Multi-photon resonance enhanced super high-order harmonic generation

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Chinese Physics B 2010年第11期19卷 280-289页

作者：林正喆庄军宁西京 Applied Ion Beam Physics Laboratory Institute of Modern PhysicsDepartment of Nuclear Science and TechnologyFudan University Department of Optical Science and Engineering Fudan University

This paper proposes highly charged ions pumped by intense laser to produce very high order harmonics. Numerical simulations and full quantum theory of Ne^9＋ ions driven by laser pulses at 1064 nm in the power range of 109 W/cm^2 1015 W/cm^2 show that the emission spectrum corresponds to the electronic transitions from the excited states to the ground state, which is very different from the spectrum of general high-order harmonic generation. In such situation, harmonic order as high as 1000 can be obtained without producing lower order harmonics and the energy conversion efficiency is close to general high order harmonic generation of hydrogen atom in the same laser field.

关键词： multi-photon excitation high-order harmonic generation

A statistical model for predicting thermal chemical reaction rate

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Chinese Physics B 2014年第5期23卷 116-122页

作者：林正喆李王尧宁西京 Institute of Modern Physics Department of Nuclear Science and TechnologyFudan University Department of Physics Fudan University State Key Laboratory of Surface Physics Fudan University

A simple model based on the statistics of individual atoms [Europhys. Lett. 94 40002 （2011）] or molecules [Chin. Phys. Lett. 29 080504 （2012）] was used to predict chemical reaction rates without empirical parameters, and its physical basis was further investigated both theoretically and via MD simulations. The model was successfully applied to some reactions of extensive experimental data, showing that the model is significantly better than the conventional transition state theory. It is worth noting that the prediction of the model on ab initio level is much easier than the transition state theory or unimolecular RRKM theory.

关键词： chemical reaction rate transition state theory unimolecular reaction bimolecular reaction

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一种制备单原子碳链的方案

物理学报 2010年第9期59卷 6438-6442页

作者：曹荣根王音林正喆明辰庄军宁西京复旦大学材料科学系上海200433 复旦大学现代物理研究所上海200433 复旦大学核科学与技术系上海200433 教育部应用离子束物理重点实验室复旦大学光科学与工程系上海200433

考虑到迄今为止实验上尚不能制备含有上百个原子的自由单原子链,本文提出利用探针从graphene中拉伸较长单原子碳链的设想,并通过分子动力学计算发现,室温下可以利用C60探针以1m/s的速度从graphene的zigzag边缘拉出较长的一维单原子碳链... 详细信息

考虑到迄今为止实验上尚不能制备含有上百个原子的自由单原子链,本文提出利用探针从graphene中拉伸较长单原子碳链的设想,并通过分子动力学计算发现,室温下可以利用C60探针以1m/s的速度从graphene的zigzag边缘拉出较长的一维单原子碳链,为实验提供了一种制备单原子碳链的可能方案.

关键词：碳链一维分子动力学探针

Simple statistical model for predicting thermal atom diffusion on crystal surfaces

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Chinese Physics B 2013年第11期22卷 458-462页

作者：于卫锋林正喆宁西京 Institute of Modern Physics Department of Nuclear Science and Technology Applied Ion Beam Physics Laboratory Fudan University

A simple model based on the statistics of single atoms is developed to predict the diffusion rate of thermal atoms in （or on） bulk materials without empirical parameters. Compared with vast classical molecular-dynamics simulations for predicting the self-diffusion rate of Pt, Cu, and Ar adatoms on crystal surfaces, the model is proved to be much more accurate than the Arrhenius law and the transition state theory. Applying this model, the theoretical predictions agree well with the experimental values in the presented paper about the self-diffusion of Pt （Cu） adatoms on the surfaces.

关键词： adatoms diffusion Arrhenius law transition state theory molecular dynamics simulations

Theoretical investigation on isomer formation probability and free energy of small C clusters

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Chinese Physics B 2015年第6期24卷 622-628页

作者：林正喆 School of Physics and Optoelectronic Engineering Xidian University

Molecular dynamics simulations and free energy calculations are employed to investigate the evolution, formation probability, detailed balance, and isomerization rate of small C cluster isomer at 2500 K. For C10, the isomer formation probability predicted by free energy is in good agreement with molecular dynamics simulation. However, for C20, C3o, and C36, the formation probabilities predicted by free energy are not in agreement with molecular dynamics simulations. Although the cluster systems are in equilibrium, detailed balance is not reached. Such results may be attributed to high transformation barriers between cage, bowl, and sheet isomers. In summary, for mesoscopic nanosystems the free energy criterion, which commonly holds for macroscopic systems in dynamic equilibrium, may not provide a good prediction for isomer formation probability. New theoretical criterion should be further investigated for predicting the isomer formation probability of a mesoscopic nanosystem.

关键词： isomer formation probability isomer free energy

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团簇异构体生长概率的理论预测

物理学报 2010年第5期59卷 3445-3449页

作者：韩小静王音林正喆张文献庄军宁西京复旦大学现代物理研究所教育部应用离子束物理重点实验室上海200433 复旦大学光科学与工程系上海200433

由于实验表征团簇结构的困难,理论预测团簇在生长过程中各种异构体的生成概率便十分重要.考虑到分子动力学可模拟高温时各异构体的相对丰度,把问题归结为高温时所形成的各种异构体在室温环境中如何转化,并建立了统计力学模型,得到了异... 详细信息

由于实验表征团簇结构的困难,理论预测团簇在生长过程中各种异构体的生成概率便十分重要.考虑到分子动力学可模拟高温时各异构体的相对丰度,把问题归结为高温时所形成的各种异构体在室温环境中如何转化,并建立了统计力学模型,得到了异构体相互演化所需时间与环境温度的解析关系.以C12团簇为例,在2500K时所形成的最可几异构体在室温环境中需要超过1012年才能转化为最低势能异构体.

关键词：团簇异构体统计物理分子动力学

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力学中链条下落问题的探讨

物理通报 2023年第6期 23-26,30页

作者：林正喆陈熙西安电子科技大学物理学院陕西西安710071

在经典力学教学中,链条运动问题是连续变形体动力学中的典型问题.对此类问题的课堂教学常见示例进行了研究,指出理论分析与实际情况的不符之处,并运用力学原理进行分析,提出与事实更加接近的理论模型.研究结论可作为新内容在力学课堂教... 详细信息

在经典力学教学中,链条运动问题是连续变形体动力学中的典型问题.对此类问题的课堂教学常见示例进行了研究,指出理论分析与实际情况的不符之处,并运用力学原理进行分析,提出与事实更加接近的理论模型.研究结论可作为新内容在力学课堂教学中进行介绍,使学生深入认识力学基本原理,提高运用力学原理解决实际问题的能力.

关键词：连续变形体动量定理角动量定理

对经典力学中的轨道角动量和自转角动量的探讨

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大学物理 2022年第8期41卷 15-18页

作者：林正喆陈熙西安电子科技大学物理与光电工程学院陕西西安710071

角动量是力学中的重要概念.本文建立了经典力学中质点系的轨道角动量和自转角动量的概念,使经典力学的理论体系更加完备,并通过几个例子阐述其应用意义.在经典力学中引入轨道角动量和自转角动量的概念,能够使学生加深对角动量的理解.

关键词：经典力学轨道角动量自转角动量

Origin of itinerant ferromagnetism in two-dimensional Fe3GeTe2

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Chinese Physics B 2021年第4期30卷 143-148页

作者：陈熙林正喆程丽蓉 School of Physics and Optoelectronic Engineering Xidian University

Magnetic order in two-dimensional systems was not supposed to exist at finite *** recent years,the successful preparation of two-dimensional ferromagnetic materials such as CrI,CrGeTe,and FeGeTeopens up a new chapter in the remarkable field of two-dimensional ***,we report on a theoretical analysis of the stability of ferromagnetism in *** uncover the mechanism of holding long-range magnetic order and propose a model to estimate the Curie temperature of *** results reveal the essential role of magnetic anisotropy in maintaining the magnetic order of two-dimensional *** theoretical method used here can be generalized to future research of other magnetic two-dimensional systems.

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