Ali Mubashar, Yousaf Masood, Munir Junaid, Iqbal Khan M Junaid
Department of Physics, University of Education, Lahore, Pakistan.
Department of Physics, University of Education, Lahore, Pakistan.
J Mol Graph Model. 2024 Jan;126:108638. doi: 10.1016/j.jmgm.2023.108638. Epub 2023 Sep 21.
Dynamical variation of physical properties in a controllable fashion provides exciting possibilities to obtain multifunctional materials. In this work, layer-sliding is employed to modify the structural, interfacial electronic and optical properties of unintercalated and Mg-intercalated two-dimensional (2D) van der Waals heterostructure (vdW-HS) consisting of buckled silicene and hexagonal boron nitride (hBN). The most stable stacking configuration of silicene over hBN is screened out and then intercalated with Mg at the interface. Dynamical-dependent changes in the properties of vdW-HS are performed by sliding silicene over hBN monolayer in the absence and presence of the intercalant. Layer-sliding is carried out in equal length intervals, and various parametric quantities related to the physical characteristics of the vdW-HS are repeatedly calculated and compared. Apart from various parametric quantities, stability of unintercalated and Mg-intercalated vdW-HS is also checked by means of relative total energies, binding energies and vdW gaps along the sliding pathway. Comparison of binding energies shows that the un-slided, half-slided, and fully-slided Mg-intercalated vdW-HS are 1.52, 1.44 and 1.42 eV more stable than the unintercalated vdW-HS. Opening of a small band gap of 12, 31 and 28 meV for un-slided, half-slided and fully-slided unintercalated vdW-HS, respectively, is worth mentioning. To study the interfacial electronic behavior, planar average charge density difference (Δρ) and charge transfer (ΔQ) are also calculated and varied via layer-sliding. Further, we calculated diverse optical spectra such as the complex dielectric function (DF), electron energy loss function [L(ω)], diagonal components of dielectric tensor [ε(iω)], refractive index [n(ω)], extinction coefficient [k(ω)], absorption coefficient [α(ω)], and reflectivity [R(ω)] for un-slided, half-slided and fully-slided unintercalated and Mg-intercalated vdW-HS. Interestingly, the polarization and energy losses have been reduced in the case of Mg-intercalated vdW-HS. The suggested layer-sliding method can be established as a general scheme for bringing multifunctionality into a layered material.
以可控方式实现物理性质的动态变化为获得多功能材料提供了令人兴奋的可能性。在这项工作中，采用层滑动来改变由弯曲硅烯和六方氮化硼（hBN）组成的未插层和Mg插层二维（2D）范德华异质结构（vdW-HS）的结构、界面电子和光学性质。筛选出硅烯在hBN上最稳定的堆叠构型，然后在界面处插入Mg。通过在不存在和存在插层剂的情况下使硅烯在hBN单层上滑动，实现vdW-HS性质的动态相关变化。层滑动以相等的长度间隔进行，并反复计算和比较与vdW-HS物理特性相关的各种参数量。除了各种参数量外，还通过沿滑动路径的相对总能量、结合能和范德华能隙来检查未插层和Mg插层vdW-HS的稳定性。结合能的比较表明，未滑动、半滑动和完全滑动的Mg插层vdW-HS分别比未插层的vdW-HS稳定1.52、1.44和1.42 eV。未滑动、半滑动和完全滑动的未插层vdW-HS分别打开了12、31和28 meV的小带隙，这值得一提。为了研究界面电子行为，还通过层滑动计算并改变了平面平均电荷密度差（Δρ）和电荷转移（ΔQ）。此外，我们计算了未滑动、半滑动和完全滑动的未插层和Mg插层vdW-HS的各种光谱，如复介电函数（DF）、电子能量损失函数[L(ω)]）、介电张量的对角分量[ε(iω)]）、折射率[n(ω)]）、消光系数[k(ω)]）、吸收系数[α(ω)]）和反射率[R(ω)]）。有趣的是，在Mg插层vdW-HS的情况下，极化和能量损失有所降低。所提出的层滑动方法可以作为一种使层状材料具有多功能性的通用方案。
