He原子与表面的准弹性散射：相互作用吸附物动力学的随机描述
Quasielastic He atom scattering from surfaces: A stochastic description of the dynamics of interacting adsorbates
摘要：
研究金属表面上粒子的扩散和低频振动运动是极其重要的，它提供了关于吸附物-基底和基底-基底相互作用的性质的有价值的信息。特别是，在扩散峰中观察到的实验加宽，随着覆盖率的增加，通常被解释为通过广泛的分子动力学计算的Langevin框架内的吸附物之间的偶极-偶极样的相互作用。在这里，我们提出了一种替代的方式来解释这种扩大通过一个纯粹的随机描述，即相互作用的单吸附近似，其中考虑两个噪声源：（1）高斯白噪声占表面摩擦和温度，和（2）白散粒噪声取代吸附之间的相互作用势。标准Langevin数值模拟的平面和波纹表面（与一个可分离的潜力）说明了Na原子在Cu（100）表面上的动力学相当好地符合从简单的模型（自由粒子和非谐振子）的解析表达式时，假设高斯近似。对于受抑平移模式峰值也预期类似的加宽。
英文摘要：
The study of diffusion and low frequency vibrational motions of particles on metal surfaces is of paramount importance; it provides valuable information on the nature of the adsorbate-substrate and the substrate-substrate interactions. In particular, the experimental broadening observed in the diffusive peak with increasing coverage is usually interpreted in terms of a dipole-dipole like interaction among adsorbates via extensive molecular dynamics calculations within the Langevin framework. Here we present an alternative way to interpret this broadening by means of a purely stochastic description, namely the interacting single adsorbate approximation, where two noise sources are considered: (1) a Gaussian white noise accounting for the surface friction and temperature, and (2) a white shot noise replacing the interaction potential between adsorbates. Standard Langevin numerical simulations for flat and corrugated surfaces (with a separable potential) illustrate the dynamics of Na atoms on a Cu(100) surface which fit fairly well to the analytical expressions issued from simple models (free particle and anharmonic oscillator) when the Gaussian approximation is assumed. A similar broadening is also expected for the frustrated translational mode peaks.
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