一种制备单原子碳链的方案

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1 m/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     

铂纳米颗粒生长和表面结构的理论预测

本文应用最近所建立的凝结势模型[2009物理学报583293;2009J.Chem.Phys.130164711]来确定铂纳米颗粒的表面结构,利用分子动力学模拟验证了该模型的可靠性.基于该模型所进行的第一性原理计算表明,各种形状的铂颗粒表面都以fcc的(111)面为主(约80%),(100)面形成的概率约10%,该结果与已有实验观测相符合.由于凝结势计算简单,该模型应是一种从理论上确定纳米颗粒表面结构的简便方法.     

团簇异构体生长概率的理论预测

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2500 K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     

Simple statistical model for predicting thermal atom diffusion on crystal surfaces

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.     

Multi-photon resonance enhanced super high-order harmonic generation

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 10 9 W/cm 2 ～ 10 15 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.     

A statistical model for predicting thermal chemical reaction rate

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.