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中文摘要：
采用分子动力学方法对液态Ga As在1×10~（10） K/s冷速下的快速结晶过程进行模拟,并采用双体分布函数、原子平均能量、键角分布函数、二面角分布函数和可视化等方法对凝固过程的微观结构变化进行分析.结果表明：凝固过程中,Ga As的结晶温度T_c为1460 K,当温度高于T_c时,体系处于液态无规网络结构;当温度低于T_c时,Ga和As原子迅速形核结晶,形成闪锌矿为主的多晶结构,并在晶界处形成共晶格孪晶结构,其中晶界处形成一层纤锌矿结构.在温度低于520 K时,As原子偏聚形成简单立方结构As_8.
英文摘要：
The technological importance of compound semiconductor GaAs are increasing because of their use in optoelectronic and microelectronic applications. Due to the high conversion efficiency and carrier mobility, GaAs can also be applied in solar cells and the recent study upon GaAs nanowires and their heterostructures has revealed that the conversion efficiency of GaAs nanowire array solar cells conversion is high up to 15.3%. Early the liquid and amorphous properties of GaAs were investigated by employing the first-principles calculations. The emergence of semi-empirical potential and the improvement of computer level have promoted the research and application of molecular dynamics （MD） simulation. MD simulation has now become one of the typical modeling methods at the molecular scale. The simulation is based on the known physical approximation of all particles in the system to solve the equation of motion, and obtain the atomic motion trajectory. Analytical potentials is very important in MD simulation as it is not feasible to solve the Hamiltonian by means of quantum-mechanical methods with huge computational complexity. Abell-Tersoff potential function is a short-ranged bond-order algorithm, which depends on bond lengths and bond angles and hence accesses information about the atomic structure. So it is suitable for simulating covalent bond species. Generally used for the IV elements and compounds like silicon, carbon, and others, but for the III-V compound semiconductor it is not very accurate due to the ionic bonds. Usually the modified tersoff potential, by the addition of Coulomb term, the modified exclusion potential and the truncation parameter, is used to simulate such semiconductor materials. Many studies on the bulk, surface and elastic properties of GaAs by means of MD method, are in good agreement with the experimental results. In this paper Karsten Albe＇s Tersoff potential is adopted as it allows one to model a wide range of properties of GaAs compound structure. GaAs has two kinds of tetrahedra
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