论文标题
在大型应变和SI中的复杂负荷下，预测应力 - 应变关系和弹性不稳定性的五度弹性潜力
Fifth-degree elastic potential for predictive stress-strain relations and elastic instabilities under large strain and complex loading in Si
论文作者
论文摘要
在简单和复杂的系统中都观察到，复杂负载下的材料会形成较大的应变，并经常通过弹性不稳定过渡。在这里，我们以$ 5^{th} $ - 通过将误差相对于密度功能理论（DFT）结果最小化，以$ 5^{th} $ - 订单弹性电位在较大的应变下呈现Si i。用于任意复合载荷的Cauchy应力 - 拉格朗日应变曲线与DFT结果相当，包括弹性不稳定性驱动Si I $ \ rightarrow $ II相变（PT）和剪切不稳定性。在立方轴向应力作用下的Si i $ \ rightarrow $ II的PT条件与DFT预测一致。这种弹性潜在允许研究弹性不稳定性和定向依赖性，从而导致不同的PT，滑动，孪生或断裂，从而为在极端负载下的晶体行为连续模拟提供了基本基础。
Materials under complex loading develop large strains and often transition via an elastic instability, as observed in both simple and complex systems. Here, we present Si I under large strain in terms of Lagrangian strain by an $5^{th}$-order elastic potential found by minimizing error relative to density functional theory (DFT) results. The Cauchy stress-Lagrangian strain curves for arbitrary complex loadings are in excellent correspondence with DFT results, including elastic instability driving Si I$\rightarrow$II phase transformation (PT) and the shear instabilities. PT conditions for Si I$\rightarrow$II under action of cubic axial stresses are linear in Cauchy stresses in agreement with DFT predictions. Such elastic potential permits study of elastic instabilities and orientational dependence leading to different PTs, slip, twinning, or fracture, providing a fundamental basis for continuum simulations of crystal behavior under extreme loading.
