Structure and Madelung energy of spherical Coulomb crystals.
Structure and Madelung energy of spherical Coulomb crystals.
复制标题
球形库仑晶体的结构和马德隆能量。
DOI：
10.1103/physreva.44.4506
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发表时间：
1991
期刊：
影响因子：
--
通讯作者：
V. Avilov
中科院分区：
文献类型：
--
作者：
R. W. Hasse;V. Avilov
借助分子动力学计算机模拟，我们研究了N= 2-5000个强相关带电粒子系统在径向谐波外约束力及其相互库仑力影响下的平衡构型。温度远低于结晶点；即，库仑与动能之比大至 Г= 10 9。粒子排列在同心球壳中，壳间距离近似恒定。在表面上，六角形结构非常明显。将计算出的半径、占据数和每个粒子的能量与经典几何和壳模型的结果进行比较，其中均匀带电壳已针对六边形表面占据进行了校正。闭壳粒子数也与多层二十面体的粒子数非常吻合。从计算机模拟中，我们提取了 -0.8926 的马德隆（过剩）能量，该能量接近于平面六边形表面校正的壳模型的理论值 -0.8923，但大于无限几何晶格的理论值 -0.8944 和 bcc 值 -0.8959。表面能效应为正，数量级为 N− 1/3。
With the help of molecular-dynamics computer simulations, we study the equilibrium configurations of systems of N= 2–5000 strongly correlated charged particles under the influence of a radial harmonic external confining force and their mutual Coulomb forces. The temperature is well below the crystallization point; ie, the ratio of Coulomb to kinetic energy is as large as Γ= 10 9. The particles arrange in concentric spherical shells with approximately constant intershell distances. On the surfaces plane hexagonal structures are well pronounced. The calculated radii, occupation numbers, and energies per particle are compared with results of classical geometrical and shell models with homogeneously charged shells corrected for hexagonal surface occupation. The closed-shell particle numbers also agree well with those of multilayer icosahedra. From the computer simulations we extract a Madelung (excess) energy of-0.8926, which is close to the theoretical value of the shell model corrected for plane hexagonal surfaces,-0.8923, but larger than the one of the infinite geometrical lattice,-0.8944, and of the bcc value of-0.8959. Surface-energy effects are positive and of the order of N− 1/3.