Pressure-induced novel structure with graphene-like boron-layer in titanium monoboride

The recent discovery of the novel boron-framework in boron-rich metal borides with complex structures and intriguing features under high pressure has stimulated the search into the unique boron-network in the metal monoborides or boron-deficient metal borides at high pressure. Herein, based on the particle swarm optimization algorithm combined with first-principles calculations, we thoroughly explored the structural evolution and properties of TiB up to 200 GPa. This material undergoes a pressure-induced phase transition of $Pnma$ $\to $ $Cmcm$ $\to $ $Pmmm$. Besides of two known phases $Pnma$ and $Cmcm$, an unexpected orthorhombic $Pmmm$ structure was predicted to be energetically favored in the pressure range of 110.88-200 GPa. Intriguingly, the B covalent network eventually evolved from a one-dimensional zigzag chain in $Pnma$-TiB and $Cmcm$-TiB to a graphene-like B-sheet in $Pmmm$-TiB. On the basis of the microscopic hardness model, the calculated hardness ($H_{\rm v}$) values of $Pnma$ at 1 atm, $Cmcm$ at 100 GPa, and $Pmmm$ at 140 GPa are 36.81 GPa, 25.17 GPa, and 15.36 GPa, respectively. Remarkably, analyses of the density of states, electron localization function and the crystal orbital Hamilton population (COHP) exhibit that the bonding nature in the three TiB structures can be considered as a combination of the B-B and Ti-B covalent interactions. Moreover, the high hardness and excellent mechanical properties of the three TiB polymorphs can be ascribed to the strong B-B and Ti-B covalent bonds.     

Origin8.0在普朗克常数测定实验中的应用

本文简单描述了Origin软件的主要功能,并以普朗克常数测定实验为例,介绍了Origin软件在近代物理实验中的数据处理过程.研究结果表明利用该软件处理物理实验数据能有效避免手工处理所带来的误差,并且能准确直观地处理实验数据.因此,作为一种常用数据处理方法非常适合在近代物理实验教学中使用.     

SbS电子基态及激发态势能曲线和振动能级的理论研究

运用多参考组态相互作用(MRCI+Q)方法,对硫化锑(SbS)能量最低的3个?-S离解极限的所有电子态以及考虑自旋-轨道耦合效应后分裂所得的Ω态进行了计算.得到27个?-S电子态及能量最低的12个Ω态的电子结构、光谱常数和振动能级等信息. Sb原子和S原子能级的计算值与实验值相符很好.分析表明自旋-轨道耦合效应对光谱常数与振动能级的影响总体上并不显著.对X(3/2)→X(1/2), 2(1/2)→X(1/2), 4(1/2)→X(1/2), 5(1/2)→X(1/2)及6(1/2)→X(1/2)跃迁的振动光谱进行了模拟与分析,其中X(3/2)→X(1/2)谱带位于中红外波段,其他谱带均位于可见光波段.此外,对氮族元素硫化物的电子态进行了验证计算,计算结果与已有实验结果吻合较好,体现了同族元素代换后相关物性的渐变规律性.     

网络驱动的未识甲骨字特性及场景语义预测

甲骨学的研究具有重要的文化价值和传承意义，可以极大提高国家的文化自信。未识甲骨字的语义预测是甲骨学研究中最主要的问题，也是传统甲骨学研究中最棘手的问题。现有的计算机技术辅助研究方法无法预测未识甲骨字的语义。利用复杂网络对甲骨文进行了抽象和理解，并对未识甲骨字的场景语义进行预测。首先，以甲骨拓片为基础数据，通过建模构建甲骨字网络；其次，在甲骨字网络之上，分析未识甲骨字的重要性、信息丰富度、闭合性等特性，为预测未识甲骨字的场景语义提供理论依据；最后，根据网络特性和甲骨拓片的上下文语境预测未识甲骨字的场景语义。构建的未识甲骨字特性体系以及预测未识甲骨字的场景语义思路为破译其他未识甲骨字的语义奠定了基础，有助于推动甲骨文考释的进程。