Ag2La分子的结构与势能函数

采用密度泛函理论DFT中的UB3LYP方法,对Ag2La分子的结构进行优化,得到Ag2La分子基态结构为具有C2v对称性的弯曲结构,电子态为2A1,结合能为3.48eV。采用最小二乘法拟合出Ag2和AgLa分子的Murrell-Sorbie势能函数,在此基础上推导出光谱数据和力常数;通过多体展示理论导出基态Ag2La分子的势能函数,其等值势能图准确再现了Ag2La分子的结构特征及其势阱深度与位置。     

Discovery of Two-Dimensional Quantum Spin Hall Effect in Triangular Transition-Metal Carbides

Though the quantum spin Hall effect(QSHE) in two-dimensional(2 D) crystals has been widely explored, the experimental realization of quantum transport properties is only limited to HgTe/CdTe or InAs/GaSb quantum wells. Here we employ a tight-binding model on the basis of d_(z~2), d_(xy), and d_(x~2-y~2) orbitals to propose QSHE in the triangular lattice, which are driven by a crossing of electronic bands at the Γ point. Remarkably, 2 D oxidized Mxenes W_2 M_2 C_3 are ideal materials with nontrivial gap of 0.12 eV, facilitating room-temperature observations in experiments. We also find that the nontrivially topological properties of these materials are sensitive to the cooperative effect of the electron correlation and spin-orbit coupling. Due to the feasible exfoliation from its 3 D MAX phase, our work paves a new direction towards realizing QSHE with low dissipation.