Sun Yimin
Shenyang Institute of Engineering, Shenyang, 110136, China.
J Mol Model. 2024 Mar 28;30(4):112. doi: 10.1007/s00894-024-05913-4.
This study investigates the dynamic stability of monolayers MoS, WS, and MoS/WS van der Waals heterostructures (vdWHs) and the influence of shear strain on their electronic properties. The computational results of the binding energy and phonon dispersion demonstrate the excellent dynamic stability of MoS/WS vdWHs. The MoS/WS vdWH, with a type-II band alignment and an indirect bandgap, reduces electron-hole recombination, enhancing the efficiency and performance of optoelectronic devices. Under shear strain, the bandgap size and type of monolayers MoS, WS, and MoS/WS vdWHs were effectively modulated, along with the interlayer charge redistribution in the MoS/WS vdWHs. This work reveals the tunability of the electronic properties of monolayers MoS, WS, and MoS/WS vdWHs under shear strain, offering new possibilities and solutions for developing optoelectronic devices, sensors, and related fields.
This work employed the CASTEP module within the Materials Studio software package for first-principles calculations. Ultrasoft pseudopotentials were employed during geometry optimizations to account for ion-electron interactions using the GGA-PBE functional for exchange-correlation potentials. The electronic configurations of the S, Mo, and W atoms were chosen as their typical arrangements: (3sp), (4spd5s), and (5spd6s), respectively. A vacuum layer of 20 Å was added to avoid interactions between the atomic layers. A cutoff energy of 500 eV was set for structural optimization and self-consistent calculations, with k-point grids of 6 × 6 × 1 and 9 × 9 × 1. During the structural optimization process, the energy convergence criterion was set to 1 × 10 eV, and the thresholds for interatomic forces and stresses were set to 0.01 eV/Å and 0.01 GPa, respectively. Grimmer's DFT-D2 correction accounted for the interlayer vdW interactions in the MoS/WS vdWH, while the phonon dispersion was calculated using the linear response method.
本研究调查了单层MoS、WS以及MoS/WS范德华异质结构（vdWHs）的动态稳定性，以及剪切应变对其电子性质的影响。结合能和声子色散的计算结果表明MoS/WS vdWHs具有出色的动态稳定性。具有II型能带排列和间接带隙的MoS/WS vdWHs减少了电子-空穴复合，提高了光电器件的效率和性能。在剪切应变下，单层MoS、WS以及MoS/WS vdWHs的带隙大小和类型得到有效调制，同时MoS/WS vdWHs中发生了层间电荷重新分布。这项工作揭示了单层MoS、WS以及MoS/WS vdWHs在剪切应变下电子性质的可调性，为开发光电器件、传感器及相关领域提供了新的可能性和解决方案。
本工作使用Materials Studio软件包中的CASTEP模块进行第一性原理计算。在几何优化过程中采用超软赝势来考虑离子-电子相互作用，使用GGA-PBE泛函来计算交换关联势。S、Mo和W原子的电子构型分别选为其典型排列：(3sp)、(4spd5s)和(5spd6s)。添加了20 Å的真空层以避免原子层之间的相互作用。结构优化和自洽计算的截止能量设置为500 eV，k点网格为6×6×1和9×9×1。在结构优化过程中，能量收敛标准设置为1×10 eV，原子间力和应力的阈值分别设置为0.01 eV/Å和0.01 GPa。Grimmer的DFT-D2校正考虑了MoS/WS vdWHs中的层间范德华相互作用，而声子色散则使用线性响应方法计算。
