AI 中文总结
本研究通过实时光密度泛函理论从头计算，探究O、Mg入射粒子穿过块状Al时电子阻止本领的Z1振荡与电荷态，发现振荡对传播方向敏感，临界速度范围为低于0.1 a.u.至高于1 a.u.，且电荷态量化结果一致，揭示了芯电子退屏蔽及耗散的相关机制。
AI 中文摘要
入射原子核向其穿过的物质的电子转移能量的速率，取决于该入射粒子的电荷Q=eZ1。在低入射粒子速度下，摩擦系数已知会随原子序数Z1振荡，因为芯电子随入射粒子运动并屏蔽其电荷。有效电荷随速度增大而增加，振荡随之消失。本研究通过从头计算方法，利用实时光密度泛函理论，计算O和Mg入射粒子穿过块状Al时的电子阻止本领，以此探究该效应。两种入射粒子分别对应第一次Z1振荡的最大值和最小值。研究发现，尽管Al在诸多用途中是相当理想的金属，但该振荡对传播方向极为敏感。在所探究的轨迹中，振荡消失的临界速度范围为低于0.1 a.u.至高于1 a.u.。通过Hirshfeld和Voronoi分析独立量化电荷态，尽管二者划分方法差异极大，所得结果却高度一致，且与基于阻止本领本身的有效定义结果也一致。这些结果显示，随着速度增大，入射粒子的芯电子逐渐退屏蔽，与预期定性相符。然而，实空间电子密度图呈现出更丰富的图像，其中退屏蔽部分源于入射粒子后方拖尾的电子，这提示可能存在现象学描述，用以校正超出净电荷的多极子密度变形，这些图还为芯电子的耗散提供了见解。
英文摘要
The energy transfer rate from a projectile nucleus to the electrons of the matter it traverses depends on the charge of that projectile, Q= e Z1. At low projectile velocities the friction coefficient is known to oscillate with atomic number Z1, since core electrons travel with the projectile screening its charge. The effective charge increases with velocity and oscillations disappear. That effect is studied here calculating electronic stopping power from first principles for O and Mg projectiles shooting through bulk Al, using real-time time-dependent density-functional theory. Both projectiles represent maximum and minimum of the first Z1 oscillation, respectively. The oscillation is found to be very sensitive to the direction of propagation, in spite of Al being quite an ideal metal for many purposes. The critical velocity for the oscillation disappearance ranges between below 0.1 a.u. and beyond 1 a.u. for the explored trajectories. The charge state is independently quantified with Hirshfeld and Voronoi analyses, offering remarkably consistent results in spite of their very different partition methods, as well as with an effective definition based on the stopping power itself. They display a gradual undressing of the projectile's core electrons with increasing velocity in qualitative accordance with expectations. However, electron density plots in real space present a richer picture in which the undressing is partly due to the electrons trailing behind the projectile, suggesting possible phenomenological descriptions correcting for the deformation of the density in terms of multipoles beyond the net charge. The plots also offer insights into dissipation by core electrons.
Comments12 pages, 15 figures
