Na_n(5≤n≤10)小团簇相变

Phase transitions of sodium small clusters Na_n(5≤n≤10)

采用紧束缚的分子动力学模型,对Na_n(5≤n≤10)小团簇的键长涨落、势能、热容量等熔化性质在50 K～1500 K温区进行了模拟研究,结果表明:它们发生两次相变,一种在230 K～300 K的温度范围内,依次有块体玻璃态转变;一种在550 K～870 K温度段,依次经历了熔化相变.同时也得到随着团簇体系的减小,势能由下向上排列的曲线,即体系的势能由低变高.

Based on the tight-binding molecular dynamics simulations, the melting properties for small sodium clusters Nan（5≤n≤10） have been studied from 50 K to 1500 K. The averaged nearest-neighbor distance, the potential energy and the heat capacity for these clusters are investigated. They seems to undergo two phase transitions,a solid-glass transition in the temperature range of 230-300 K, and a melting transition as the temperature increase to the range of 550-870 K. Also, we find that the potential energy-temperature curves ranged from low to high for these clusters, i. e. , the potential energy will increase with the decrease of the number of the cluster atoms.