论文标题
通过第一原则模拟和拉曼光谱分析来阐明V-V二聚体在VO $ _2 $的振动特性上的作用
Unraveling the role of V-V dimer on the vibrational properties of VO$_2$ by first-principles simulations and Raman spectroscopic analysis
论文作者
论文摘要
我们使用密度功能理论以及拉曼光谱法研究了VO2的振动特性，特别是通过第一原理计算的低温M1相。我们使用扫描元GGA功能执行结构优化，并获得金属金红石和绝缘M1相的优化晶体结构，从而满足了实验得出的结构的所有预期特征。基于在零温度下优化结构周围的谐波近似，我们计算了声子特性，并将结果与实验进行比较。我们表明，我们计算出的状态声子密度与先前的中子散射实验非常吻合。此外，我们在金红石相中重现了声子软化，以及在M1相中的声子僵硬。通过与拉曼实验进行比较，我们发现M1相的拉曼活性振动模式与晶体结构的V-V二聚体距离密切相关。我们结合的理论和实验框架表明，拉曼光谱可以作为检测紧张的VO $ _2 $中V-V二聚体微妙变化的可靠方法。
We investigate the vibrational properties of VO2, particularly the low temperature M1 phase by first-principles calculations using the density functional theory as well as Raman spectroscopy. We perform the structural optimization using SCAN meta-GGA functional and obtain the optimized crystal structures for metallic rutile and insulating M1 phases satisfying all expected features of the experimentally derived structures. Based on the harmonic approximation around the optimized structures at zero temperature, we calculate the phonon properties and compare our results with experiments. We show that our calculated phonon density of states is in excellent agreement with the previous neutron scattering experiment. Moreover, we reproduce the phonon softening in the rutile phase as well as the phonon stiffening in the M1 phase. By comparing with the Raman experiments, we find that the Raman-active vibration modes of the M1 phase is strongly correlated with the V-V dimer distance of the crystal structure. Our combined theoretical and experimental framework demonstrates that Raman spectroscopy could serve as a reliable way to detect the subtle change of V-V dimer in the strained VO$_2$.
