Nanoscale Molecular Dynamics Simulaton of Shock Compression of Silicon

Abstract

Abstract. Shear stresses are the driving forces for the creation of both point and extended defects in crystals subjected to high pressures and temperatures. Recently, we observed anomalous elastic materials response in shock-compressed silicon and diamond in the course of our MD simulations and were able to relate this phenomenon to non-monotonic dependence of shear stress on uniaxial compression of the material. Here we report results of combined density functional theory (DFT) and classical interatomic potentials studies of shear stresses in shock compressed covalent solids such as diamond and silicon for three low-index crystallographic directions, <100>, <110>, <111>. We observed a non-monotonic dependence of DFT shear stresses for all three crystallographic directions which indicates that anomalous elastic response of shock compressed material is a real phenomenon and not an artifact of interatomic potentials used in MD simulations.

Dynamics of Ultrafast Phase Transitions in (001) Si on the Shock-Wave Front

“…During propagation, the amplitude of the shock wave drops and the width of the shock-wave front is increased. The peak shock-wave velocity is about 15 km/s, which is similar to the results obtained for (111) Si [35]. The shock-wave velocity rapidly (about 2-3 ps) decays and the shock wave loses about 75% of its energy, and the corresponding particle velocity decays similarly (see Figure 4).…”

“…The phase transition mainly occurs during this time interval (when the shock wave loses 75% energy). The dependence between shock and particle velocity is presented in Figure 4 (see inset) and represents its shock adiabat [35]. Under pressures achieved under such an impact, a compression of Si becomes inelastic and exhibits the "anomalous" elastic waves [36].…”

Development of Path Integral Monte Carlo Simulations with Localized Nodal Surfaces for Second-Row Elements

“…A number of dynamic shock compression experiments have been performed [39][40][41][42][43][44][45]. Shock-compressed silicon has been studied theoretically with several classical [46][47][48][49] and one DFT-MD simulation [50] that investigated pressures up…”

“…A number of dynamic shock compression experiments have been performed [39][40][41][42][43][44][45]. Shock-compressed silicon has been studied theoretically with several classical [46][47][48][49] and one DFT-MD simulation [50] that investigated pressures up to 500 GPa and temperatures up to 10 4 K. Dynamical properties of shocked silicon plasma states have also been studied extensively by theoretical approaches [51][52][53][54][55].…”