First principle calculation of physical properties of barium based chalcogenides BaM₄S₇ (M = Ga, Al); a DFT, DFT-D and hybrid functional HSE06 study

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• 作者：Ali Benghia ^{a.benghia@lagh-univ.dz" class="auth_mail" title="E-mail the corresponding author benghia11@gmail.com" class="auth_mail" title="E-mail the corresponding author} ; Tahar Dahame ^{t.dahame@mail.lagh-univ.dz" class="auth_mail" title="E-mail the corresponding author} ; Bachir Bentria ; ^{bentria_b@yahoo.co.uk" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Ternary chalcogenides ; Linear and nonlinear optical properties ; Hybrid functional HSE06 ; Non centrosymmetric materials ; Semiconductor ; DFT-D correction
• 刊名：Optical Materials
• 出版年：2016
• 出版时间：April 2016
• 年：2016
• 卷：54
• 期：Complete
• 页码：269-275
• 全文大小：1143 K

文摘

The electronic structure, elastic and optical properties have been calculated for the novel nonlinear optical (NLO) crystals BaQ₄S₇ (Q = Ga, Al) using plane wave pseudo-potential density functional theory (DFT) method as implemented in CASTEP and ABINIT codes. In this study we used both hybrid HSE06 and DFT-D functionals with GGA approximation. These NLO compounds, which belong to the mm2 point group, are particularly interesting because of their transparency in the mid-infrared region and wide energy band gap. We present results for electronic structure, elastic tensor coefficients, refractive indices and second order nonlinear optical susceptibilities. The calculated energy band gap and frequency dependent refractive indices as well as the NLO coefficients of BaGa₄S₇ are in good agreement with the experimental values. With no reported theoretical or experimental energy band gap and optical properties of BaAl₄S₇, we present for the first time its electronic structure and above mentioned optical coefficients. This compound has higher direct band gap with 3.74 eV, better optical birefringence and second-order NLO coefficients than most NLO compounds. The second-order NLO coefficients for BaAl₄S₇ have been calculated as d₃₁ = 3.15 pm/V, d₃₁ = 2.20 pm/V, d₃₃ = −6.31 pm/V.