（1）定义：旋轨耦合又叫自旋轨道耦合，指明了耦合电子的自旋自由度和它的轨道自由度之间的关系，这种关系提供了一种新的方式来控制电子自旋。自旋轨道耦合效应在半导体自旋电子学有很多具体应用，实际研究中根据介质材料所受力的性质和材料结构对称性可以将自旋轨道耦合效应分为Rashba自旋轨道耦合和Dressalhaus自旋轨道耦合。
Fig. 3 Spin-polarized band structure of TbO2 a for spin up b for spin down under PBE-GGA potential
（2）说明：Figure 3a, b shows the spin-polarized spin band structure for TbO2 along the higher symmetry directions R, L, Γ, X and K. Band structure for spin up channel shows a direct wide band gap of ~ 5. 8 eV along the X-symmetry axis, which is representing wide band gap semiconducting behavior. Whereas spin down channel shows a finite DOS around Fermi level, shows a small band gap of ~ 0.8 eV as compared to the spin up channel. These observations are in line with our DOS results and also reported by Kanoun et al. in their earlier study. Band structure for spin up channel shows dense bands at around −5.0 eV in the valence band which is due to Tb-4f orbitals as also observed in DOS profile. Whereas between the energy range of −5.0 to 0 eV bands are less dense and due to combined contribution of Tb-4f and O-2p orbitals. For the spin down channel, dense bands are observed between the energy ranges 0–1.0 eV in the conduction which is due to Tb-4f orbitals which is in line with DOS observation. Deep inside the conduction band, above the 5.0 eV bands are less dense and due to Tb-4f and O-2p orbitals.
文献来源：DOI：10.1140/epjp/s13360-020-00901-y
第一性原理计算的基本思想是将多个原子构成的体系看成是由多个电子和原子核组成的系统，并根据量子力学的基本原理对问题进行最大限度的“非经验性”处理。它只需要5个基本常数（m0，e，h，c，kB）就可以计算出体系的能量和电子结构等物理性质。它可以确定已知材料的结构和基础性质，并实现原子级别的精准控制，是现阶段解决实验理论问题和预测新材料结构性能的有力工具。并且，第一性原理计算不需要开展真实的实验，极大地节省了实验成本，现已被广泛应用于化学、物理、生命科学和材料学等领域。
适合的研究方向包括但不限于：催化、电池、半导体、金属材料、非金属材料、合金、纳米材料等
可以计算的体系包括但不限于：晶体、非晶、二维材料、表面、界面、固体等
常用软件：VASP，MS，CP2K，QE等
可以计算的内容包括但不限于：
材料的几何结构参数（如键长、键角、二面角、晶格常数、原子位置等）
材料的电子结构信息（如电荷密度、电荷差分密度、态密度、能带、费米能级、功函数、ELF等）
材料的光学性质（如介电常数等）
材料的力学性质（如弹性模量等）
材料的磁学性质（如磁导率等）
材料的晶格动力学性质（如声子谱等）
材料的表面性质（如吸附能，催化计算等）
复合材料的性质（异质结等内容）等等
