铜团簇(n=55)结构及能量随温度演变的Monte Carlo 模拟研究

采用Monte Carlo方法及Embeded-Atom Method作用势，以55个铜原子体系为对象，研究了高 温铜团簇的结构及能量.首先计算温度为200?K时Cu₅₅的能量及结构，其结果 与土耳 其Süleyman ?zcelik 等人的研究小组的研究结果符合很好，说明此方法是可靠的.然后， 从12000?K开始逐渐降温，间隔1000?K，每个温度点MCS为10⁶，在达到平衡时 得到体系的结构及能量.结果表明：在10000?K以上时，体系只有少数原子结合在一起成核，成核数很少，且很不稳定，单原子数较多；在10000?K到6000?K温度段，随着温度的降低，体系 结构由单原子双原子数较多渐变到有较多原子结合在一起，形成一个大的成核中心，剩余单 原子、双原子逐渐与成核中心集结；在温度5000?K达到平衡时，体系原子已经完全结合在 一起，没有单个原子存在，体系能量为-11206?eV，在进一步降温的过程中，体系结构由 5000?K时的不对称、不规则渐变到600?K时的规则、对称的双二十面体结构，能量为-168 50?eV；在可视化的显示下，得到一幅十分清晰的关于体系随温度降低的结构演变图. 关键词： 铜团簇 结构及能量 Monte Carlo 模拟 高温

Energetics and structures of high-temperature copper cluster studied by Monte Carlo method

Monte Carle method and embedded-atom potential were utilized to study the energetics and structures of high_temperature copper clusters, which contained 55 ato ms. First, we calculated the energetics and structures of Cu₅₅ at 2 00?K.T he results that we got well accord with those Suleyman Ozcelik et al obtained. I t is shown that this method is reliable. Then, the system was cooled from 12000 ?K, in a step of 1000?K, the energetics and structures were measured while th e system reached equilibrium. At each temperature, the Monte Carlo Stepsare 10 ⁶. From the simulation we found that above 10000?K, the system only contain a few atoms that are combined together and unsteady,so single atoms are getting more. Between 10000 and 6000?K, the structure of the system gradually changes to forming nucleating center, other atoms nucleated with nucleating center; Atta ined equilibrium at 5000?K, the system atom is already complete combinative tog ether without the monatomic, the energy is -11206?eV; Further lower the tempe rature, the system construction becomes from irregular、dissymmetrical to regula r、symmetrical forming a double icosahedral shape, the energy is -16850?eV; W ith visual displaying, a very clear evolving structural diagram was achieved wit h lower in temperature.
Keywords： copper cluster energetics and structures Monte Carlo method high temperature