Mohebbi Elaheh, Pavoni Eleonora, Mencarelli Davide, Stipa Pierluigi, Pierantoni Luca, Laudadio Emiliano
Department of Materials, Environmental Sciences and Urban Planning, Marche Polytechnic University 60131 Ancona Italy
Information Engineering Department, Marche Polytechnic University 60131 Ancona Italy
Nanoscale Adv. 2022 Aug 9;4(17):3634-3646. doi: 10.1039/d2na00247g. eCollection 2022 Aug 23.
We have studied the structural, electronic, magnetic, and optical properties of the VO(B) polymorph using first-principles calculations based on density functional theory (DFT). This polymorph was found to display four optimized structures namely VO(B), VO(B), VO(B), and VO(B) using the generalized gradient approximation (GGA) PBE exchange-correlation functional by including/excluding van der Waals interaction. Our derivation provides a theoretical justification for adding an on-site Coulomb value in the conventional DFT calculations to allow a direct comparison of the two methods. We predicted a zero bandgap of the VO(B) structure based on GGA/PBE. However, by GGA/PBE + U, we found accurate bandgap values of 0.76, 0.66, and 0.70 eV for VO(B), VO(B), and VO(B), respectively. The results obtained from DFT + U were accompanied by a structural transition from the metallic to semiconductor property. Here, we verified the non-magnetic characteristic of the monoclinic VO(B) phase with some available experimental and theoretical data. However, the debate on the magnetic property of this polymorph remains unresolved. Imaginary and real parts of the dielectric function, as computed with the GGA/PBE functional and the GGA/PBE + U functional, were also reported. The first absorption peaks of all considered geometries in the imaginary part of the dielectric constants indicated that the VO(B) structure could perfectly absorb infrared light. The computed static dielectric constants with positive values, as derived from the optical properties, confirmed the conductivity of this material. Among the four proposed geometries of VO(B) in this study, the outcomes obtained by VO(B) reveal good results owing to the excellent consistency of its bandgap, magnetic and optical properties with other experimental and theoretical observations. The theoretical framework in our study will provide useful insight for future practical applications of the VO(B) polymorph in electronics and optoelectronics.
我们基于密度泛函理论（DFT），采用第一性原理计算方法研究了VO(B)多晶型物的结构、电子、磁性和光学性质。通过包含/排除范德华相互作用，使用广义梯度近似（GGA）PBE交换关联泛函，发现该多晶型物呈现出四种优化结构，即VO(B)、VO(B)、VO(B)和VO(B)。我们的推导为在传统DFT计算中添加在位库仑值提供了理论依据，以便对两种方法进行直接比较。基于GGA/PBE，我们预测VO(B)结构的带隙为零。然而，通过GGA/PBE + U方法，我们分别得到VO(B)、VO(B)和VO(B)的准确带隙值为0.76、0.66和0.70 eV。从DFT + U获得的结果伴随着从金属性质到半导体性质的结构转变。在此，我们利用一些现有的实验和理论数据验证了单斜VO(B)相的非磁性特征。然而，关于这种多晶型物磁性的争论仍未解决。还报道了用GGA/PBE泛函和GGA/PBE + U泛函计算得到的介电函数的虚部和实部。介电常数虚部中所有考虑几何结构的第一个吸收峰表明VO(B)结构能够完美吸收红外光。从光学性质推导得到的具有正值的计算静态介电常数证实了这种材料的导电性。在本研究中提出的VO(B)的四种几何结构中，VO(B)得到的结果显示出良好的效果，因为其带隙、磁性和光学性质与其他实验和理论观察结果具有出色的一致性。我们研究中的理论框架将为VO(B)多晶型物在电子学和光电子学中的未来实际应用提供有用的见解。
