中文摘要：

精确原子间相互作用势函数的建立是分子动力学模拟的核心.针对α-B晶体（Rˉ3m群）,分别构建Lennard-Jones（L-J）型对势和对势型多体势,这两类势函数的构建仅需考虑晶体的原子平均结合能和几何构型参数.前者取最近邻原子间距的势函数为最小值;后者采用负指数（L-J型）函数和分段插值多项式形式来分别构造势函数,在近邻处为势能极小值,相邻极小值位置的中点引入势垒.针对完整的α-B晶体和偏离完整α-B晶体结构,首先利用第一性原理计算结果来确定势函数的参数,然后借助分子动力学的能量最小化方法优化结构,并对这两类势函数以及Tersoff势函数进行比较.结果表明：L-J对势和Tersoff势的结果与α-B晶体构型有较大偏离;而对势型多体势,无论初始晶体构型完整与否,其结果与完整α-B晶体构型比较一致.

英文摘要：

For α-boron, R3m group, Lennard-Jones （L-J） pair potential function is fitted, and a pairwise many-body potential is constructed. For constructing both interatomic potentials, only the atomic average cohesive energy and geometric information are needed. And the cohesive energy and geometry of α--boron crystal are calculated by first-principles code Castep. The fitting procedure for the potentials is as follows. For L-J potential, the minimum of the function is set to be located at the nearest neighbors. For the pairwise many-body potential, L-J potential is minimal, and the form of the function is chosen as a piecewise function, which consists of the L-J function and polynomial function. The minima of L-J potential are located at the distances between the different neighbors of atoms, and the potential barriers are at the midpoints of the distances of the two neighbor minima. L-J potential, L-J pair potential, and Tersoff potential for boron are tested and compared with each other, by energy minimization method in molecular dynamics （MD） simulation. The radial distribution function is used to analyze the structure obtained from the simulation results obtained by using different potentials. The results show that the structure after minimization deviates significantly from the initial crystal of α-boron by L-J potential, and final structure is consistent well with the initial ideal crystal, with L-J potential used. The NVT ensemble is used in MD simulation, where the temperature is set to be 2000 K, and the α-boron crystal experiences the thermodynamic evolutions for 10 fs and 100 fs, to obtain the deviated initial structures. Then the minimization by MD simulation is made to test the three potentials, which also shows that the L-J potential can give the much better result than the other two potentials.