Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, California 91125, USA.
Phys Rev Lett. 2012 Jan 27;108(4):045501. doi: 10.1103/PhysRevLett.108.045501. Epub 2012 Jan 23.
It has long been observed that brittle fracture of materials can lead to emission of high energy electrons and UV photons, but an atomistic description of the origin of such processes has lacked. We report here on simulations using a first-principles-based electron force field methodology with effective core potentials to describe the nonadiabatic quantum dynamics during brittle fracture in silicon crystal. Our simulations replicate the correct response of the crack tip velocity to the threshold critical energy release rate, a feat that is inaccessible to quantum mechanics methods or conventional force-field-based molecular dynamics. We also describe the crack induced voltages, current bursts, and charge carrier production observed experimentally during fracture but not previously captured in simulations. We find that strain-induced surface rearrangements and local heating cause ionization of electrons at the fracture surfaces.
长期以来，人们一直观察到材料的脆性断裂会导致高能电子和紫外光子的发射，但对于这种过程的原子级描述一直缺乏。我们在这里报告了使用基于第一性原理的电子力场方法与有效核势的模拟，以描述硅晶体脆性断裂过程中的非绝热量子动力学。我们的模拟再现了裂纹尖端速度对临界能量释放率的正确响应，这是量子力学方法或传统的基于力场的分子动力学方法无法实现的。我们还描述了在断裂过程中实验观察到但以前在模拟中未捕获到的裂纹诱导电压、电流爆发和载流子产生。我们发现，应变诱导的表面重排和局部加热会导致断裂表面的电子电离。
