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利用第一性原理方法模拟了自由钒氧酞菁 (VOPc)和钒酞菁 (VPc)分子的扫描隧道显微镜 (STM)图像 ,与实验观察结果相当符合 .理论STM图像都显示出亚分子内结构 ,外围呈四叶状 .其主要差异表现在VOPc分子中心处的钒氧离子在STM图像中为一空洞 ,而在VPc分子的STM图像中钒离子为突起的亮斑 .通过分析VOPc和VPc分子的电子结构 ,对模拟结果给出自洽的理论解释 .造成两者图像显著不同的物理原因是VPc分子在费米能级附近有明显含dz2 成分的分子轨道 ,导致钒离子在STM图像中央为突起的亮斑 .而在VOPc分子中dz2 分态密度峰位由于氧原子的加入使之远离费米能级 ,使STM不能“看到”VOPc分子中钒氧离子 .
The first-principle method was used to simulate the scanning tunneling microscope (STM) images of free vanadyl phthalocyanine (VOPc) and vanadyl phthalocyanine (VPc) molecules, which is in good agreement with the experimental observations.The theoretical STM images all show intramolecular sub-intramolecular structures , The outer quadrangular.The main difference is that vanadium oxygen ions in the center of VOPc molecules in the STM image as a hole, and VPc molecules in the STM image of the bright spots of protuberance.By analyzing VOPc and VPc molecules , And gives a consistent theoretical explanation for the simulation results.The physical reason causing the two images to be significantly different is that the molecular orbital of the VPc molecule, which obviously contains the dz2 component near the Fermi level, causes the vanadium ions to be protuberant in the center of the STM image Of the bright spots.While in the VOPc molecule dz2 peak position density due to the addition of oxygen atoms away from the Fermi level, so that STM can not “see” VOPc vanadium oxygen ions.