Dai Y, Li J H, Liu B X
Advanced Materials Laboratory, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084, People's Republic of China.
J Phys Condens Matter. 2009 Sep 23;21(38):385402. doi: 10.1088/0953-8984/21/38/385402. Epub 2009 Aug 24.
An n-body potential is developed and satisfactorily applied to hcp metals, Co, Hf, Mg, Re, Ti, and Zr, in the form of long-range empirical potential. The potential can well reproduce the lattice constants, c/a ratios, cohesive energies, and the bulk modulus for their stable structures (hcp) and metastable structures (bcc or fcc). Meanwhile, the potential can correctly predict the order of structural stability and distinguish the energy differences between their stable hcp structure and other structures. The energies and forces derived by the potential can smoothly go to zero at cutoff radius, thus completely avoiding the unphysical behaviors in the simulations. The developed potential is applied to study the vacancy, surface fault, stacking fault and self-interstitial atom in the hcp metals. The calculated formation energies of vacancy and divacancy and activation energies of self-diffusion by vacancies are in good agreement with the values in experiments and in other works. The calculated surface energies and stacking fault energies are also consistent with the experimental data and those obtained in other theoretical works. The calculated formation energies generally agree with the results in other works, although the stable configurations of self-interstitial atoms predicted in this work somewhat contrast with those predicted by other methods. The proposed potential is shown to be relevant for describing the interaction of bcc, fcc and hcp metal systems, bringing great convenience for researchers in constructing potentials for metal systems constituted by any combination of bcc, fcc and hcp metals.
开发了一种n体势，并以长程经验势的形式成功应用于六方密堆积（hcp）金属钴（Co）、铪（Hf）、镁（Mg）、铼（Re）、钛（Ti）和锆（Zr）。该势能够很好地再现它们稳定结构（hcp）和亚稳结构（体心立方（bcc）或面心立方（fcc））的晶格常数、c/a比、结合能和体模量。同时，该势能够正确预测结构稳定性的顺序，并区分其稳定hcp结构与其他结构之间的能量差异。由该势导出的能量和力在截止半径处能平滑地趋于零，从而完全避免了模拟中的非物理行为。所开发的势被应用于研究hcp金属中的空位、表面缺陷、堆垛层错和自间隙原子。计算得到的空位和双空位形成能以及空位自扩散激活能与实验值和其他研究结果吻合良好。计算得到的表面能和堆垛层错能也与实验数据以及其他理论研究结果一致。计算得到的形成能总体上与其他研究结果相符，尽管本研究中预测的自间隙原子稳定构型与其他方法预测的有所不同。所提出的势被证明与描述bcc、fcc和hcp金属系统的相互作用相关，为研究人员构建由bcc、fcc和hcp金属任意组合构成的金属系统的势带来了极大便利。
