Using first-principles density functional theory, a tetragonal silicon–boron binary structure with space group P42/mnm is predicted in present work. This structure is confirmed to be dynamically and mechanically stable below 19.3 GPa, and possesses lower energy than other candidates. Based on the plane wave pseudopotential method, the electronic structure, elastic constant, bulk modulus, shear modulus, Young’s modulus, lattice thermal conductivity and phonon lifetime of P42/mnm-BSi are systematically studied. Interestingly, a four-center and six-electron delocalized π bond is found in P42/mnm-BSi, which is the most important factor for its structural stability. The optical spectra calculations reveal that P42/mnm-BSi is a wide band-gap semiconductor with an indirect band-gap of 2.5 eV and has a promising application in the photoelectric devices. The calculated lattice thermal conductivity along the [001] crystal direction is 145 Wm⁻¹ K⁻¹ that is about three times higher than that along both the [100] and [010] directions, which is originated from the different group velocity along the crystal axis. Moreover, the acoustic–optical coupling has some positive influences on lattice thermal conductivity. This study gives a fundamental understanding of the structural, electronic, elastic and heat transport properties in P42/mnm-BSi.

使用第一原理密度泛函理论，在当前工作中预测了空间群为P42 / mnm的四方硅-硼二元结构。确认该结构在19.3 GPa以下具有动态和机械稳定性，并且比其他候选材料具有更低的能量。基于平面波伪势方法，系统地研究了P42 / mnm -BSi的电子结构，弹性常数，体积模量，剪切模量，杨氏模量，晶格热导率和声子寿命。有趣的是，在P42 / mnm -BSi中发现了四中心和六电子离域的π键，这是对其结构稳定性最重要的因素。光谱计算表明P42 / mnm-BSi是具有2.5 eV的间接带隙的宽带隙半导体，在光电器件中具有广阔的应用前景。沿[001]晶体方向计算的晶格热导率为145 Wm ^-1  K ^-1，比沿[100]和[010]方向的晶格热导率高约三倍，这是由于沿晶格方向的不同基团速度引起的。晶轴。此外，声光耦合对晶格热导率有一些积极影响。这项研究对P42 / mnm -BSi中的结构，电子，弹性和热传递性质有基本的了解。