标题： 电子在理想晶体固体的应力-应变曲线中的作用 显示英文标题

标题： On the role played by electrons in the stress-strain curves of ideal crystalline solids

摘要： 固体的机械性能，即其变形与外加力之间的关系，是决定一种原本最优的材料在任何应用中是否可用的关键因素，同时也强烈影响其使用寿命。通过原子模拟理论研究了在位错密度较低的单晶上实验研究的固有晶体变形机制。在此，我们采用密度泛函理论和热力学分析来探测和分析晶体固体（铜、铝和金刚石）的电子电荷如何响应单轴应变并影响其机械性能。事实上，尽管我们的模型非常简单，并且在存在最小原子位移的情况下，我们发现铜和铝的应力-应变曲线偏离了简单的线弹性行为。从热力学的角度来看，这些曲线的特征可以解释为一阶和二阶相变。从热力学的角度来看，这些曲线的特征可以解释为一阶和二阶相变，分别来源于电子态密度的Van-Hove奇异性穿过费米能级和固体内的电子重分布。 显示英文摘要

摘要： The mechanical properties of a solid, which relate its deformation to external applied forces, are key factors in enabling or disabling the use of an otherwise optimal material in any application, strongly influencing also its service lifetime. Intrinsic crystal deformation mechanisms, investigated experimentally on single crystals with low dislocation densities, have been studied theoretically through atomistic simulations, mainly focusing on lattice-induced instabilities. Here, instead, we employ density functional theory and a thermodynamic analysis to probe and analyze the way in which the electronic charge of crystalline solids (Cu, Al and diamond) responds to uniaxial strain and affects their mechanical properties. Indeed, despite the very simple nature of our models, and in the presence of minimal atomic displacements, we find that the stress strain curves of Cu and Al deviate from a simple linear elastic behavior. Within a thermodynamics perspective, the features of such curves can be interpreted in terms of first and second order phase transitions. Within a thermodynamics perspective, the features of such curves can be interpreted in terms of first and second order phase transitions, which originate from Van-Hove singularities of the electronic density of states crossing the Fermi level and electron redistribution within the solid, respectively.