Multiscale Design of Nanostructured Ceramics for High-frequency Electromagnetic Applications

在这项研究中，我们为用于超高速大众通信设备的纳米结构材料开发了新颖和高精度的模拟方法。我们利用这些方法研究了缺陷、晶界和杂质对纳米陶瓷和半导体的电磁性质的影响。在研究期间，我们得到了以下结果：1.基于紧束缚近似的含时薛定谔方程计算了硅纳米线中的电子输运系数；2.用量子/经典混合分子动力学方法分析了杂质氢在硅晶体和晶界中的扩散过程。发现了缺陷与杂质相互作用导致H原子活化能在1000K附近及以上突然下降的可能机制。我们发现，金刚石的剩余磁化强度可能是在间隙位置插入Ni杂质时局部产生的。利用经典映射法计算了低维电子系统中捕获的电子之间的关联，从而评估了低维电子系统中的自旋极化率。通过结构和简正波分析，研究了熔化过程与振动模之间的关系。发展了超材料电磁响应的时域有限差分(FDTD)模拟方法，并将其应用于金属-绝缘体多层结构，在国内多次会议和四次特邀讲座中介绍了这些结果。

In this research, we have developed novel and highly accurate simulation methodologies for nanostructured materials that are used in ultra high-speed mass communication devices. We have applied the methods to clarify the effects of defects, grain boundaries, and impurities on electronic and magnetic properties of nanostructured ceramics and semiconductors.During the research term, we have obtained the following outcomes:1. The electronic transportation coefficient in Si nanowires has been calculated via the time-dependent Schrodinger equation based on the tight-binding approximation;2. The diffusion processes of the impurity hydrogen in a Si crystal and grain boundary were analyzed by hybrid quantum/classics molecular dynamics method. We have found possible mechanism of the sudden drop of activation energy of H atom around and above 1000K due to the interactions between the defects and the impurity.3. We have found the possibility that the residual magnetization of diamond is locally generated when Ni impurities were inserted at interstitial sites.4. The spin polarizability in low-dimensional electron system was evaluated through the correlations between electrons trapped in low-dimensional system by the classics map method.5. The structural and normal-mode analyses were performed to investigate the relationship between melting processes and the vibrational modes.6. The finite-difference time-domain (FDTD) simulation methodologies for electromagnetic responses of meta-materials were developed and applied to the metal-insulator multilayer structures.We have presented these results in a lot of domestic societies meetings and in four invited lectures.