First principles calculation on ternary stannide phase narrow band gap semiconductor Na_2MgSn

三元Stannide相窄带隙半导体Na_2MgSn的第一性原理计算(英文)

The electronic structures,chemical bonding,elastic and optical properties of the ternary stannide phase Na2MgSn were investigated by using density-fimctional theory（DFT） within generalized gradient approximation（GGA）.The calculated energy band structures show that Na2MgSn is an indirect semiconductor material with a narrow band gap 0.126 eV.The density of state（DOS）and the partial density of state（PDOS） calculations show that the DOS near the Fermi level is mainly from the Na 2p,Mg 3p and Sn5 p states.Population analysis suggests that there are strongly bonded Mg-Sn honeycomb layers in Na2MgSn.Basic physical properties,such as lattice constant,bulk modulus,shear modulus,elastic constants c（ij） were calculated.The elastic modulus E and Poisson ratio v were also predicted.The results show that Na2MgSn is mechanically stable soft material and behaves in a brittle manner.Detailed analysis of all optical functions reveals that Na2MgSn is a better dielectric material,and reflectivity spectra show that Na2MgSn promise as good coating materials in the energy regions 6.24-10.49 eV.

利用基于密度泛函理论（DFT）的广义梯度近似（GGA）研究Na2MgSn的电子结构、化学键、弹性和光学性质。能带结构显示Na2MgSn为间接带隙材料,带隙宽度为0.126 eV;态密度和分态密度计算结果表明,费米能级附近的态密度主要来自Na、Mg和Sn的p态电子;布居分析表明Na2MgSn中的化学键具有以共价性为主的混合离子-共价特征。计算得到Na2MgSn的晶格参数、体模量、剪切模量和单晶的弹性常数,由此导出弹性模量和泊松比。结果表明,Na2MgSn是力学稳定的,且具有一定的脆性。光学函数表明Na2MgSn是好的介电材料,反射谱在6.24-10.29 eV的能量范围内,Na2MgSn是较好的被覆材料。