In the dynamics of atoms and molecules at metal surfaces, electron–hole pair excitations can play a crucial role. In the case of hyperthermal hydrogen atom scattering, they lead to nonadiabatic energy loss and highly inelastic scattering. Molecular dynamics with electronic friction simulation results, based on an isotropic homogeneous electron gas approximation, have previously aligned well with measured kinetic energy loss distributions, indicating that this level of theoretical description is sufficient to describe nonadiabatic effects during scattering. In this study, we demonstrate that friction derived from density functional theory linear response calculations can also describe the experimental energy loss distributions, although agreement is slightly worse than for the simpler isotropic homogeneous electron gas approximation. We show that the apparent agreement of the homogeneous electron gas approximation with experiment arises from a fortuitous cancellation of errors as friction is overestimated close to the surface and the spin transition is neglected. Differences in frictional treatment affect single, double, and multibounce scattering trajectories in distinct ways, altering the shape of low-temperature energy loss distributions. These distinctions are largely absent at room temperature but may be measurable in future low-temperature scattering experiments.

中文翻译：

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室温氢原子散射实验不足以成为验证电子摩擦理论的基准


在金属表面的原子和分子动力学中，电子-空穴对激发可以起着至关重要的作用。在高温氢原子散射的情况下，它们会导致非绝热能量损失和高度非弹性散射。基于各向同性均相电子气体近似的电子摩擦仿真结果的分子动力学之前与测得的动能损失分布非常吻合，这表明这种理论描述水平足以描述散射过程中的非绝热效应。在这项研究中，我们证明了从密度泛函理论线性响应计算得出的摩擦也可以描述实验能量损失分布，尽管一致性比更简单的各向同性均相均质电子气近似略差。我们表明，均匀电子气体近似与实验的明显一致性是由于偶然抵消了误差，因为在靠近表面的地方摩擦力被高估了，而自旋过渡被忽略了。摩擦处理的差异以不同的方式影响单弹、双弹和多弹散射轨迹，从而改变低温能量损失分布的形状。这些区别在室温下基本上不存在，但在未来的低温散射实验中可能是可以测量的。