第一过渡金属酞菁分子的电子结构的第一性原理计算

A FIRST-PRINCIPLES STUDY ON THE ELECTRONIC STRUCTURE OF THE FIRST TRANSITION METAL PHTHALOCYANINES

对第一过渡金属酞菁化合物 (MetalPhthalocyanine,MPc,M =Sc,Ti,V ,Cr,Mn ,Fe ,Co ,Ni和Cu)的电子结构和基本物理化学性质进行了第一性原理计算 .理论模拟出来的STM图像表现出亚分子结构 ,与已有的实验观察结果相当吻合 ,且跟金属原子的d电子组态明显有关 .在小偏压条件下 ,第一过渡金属首尾端ScPc ,NiPc和CuPc分子的中央金属离子在STM图像表现为空洞 ,其他所有金属酞菁分子的中央金属离子均为亮斑 .同时还研究了ScPc和NiPc分子的STM图像与偏压的关系 ,当针尖偏压分别大于 - 0 8V和 0 7V时 ,ScPc和NiPc分子中金属离子在STM图像中不再是空洞 ,而变为突起 .计算结果表明当费米能级附近的金属酞菁分子轨道含有显著的dz2 成分时 ,中心金属离子在STM图像中为突起的亮斑 ,当显含dz2 的能级与费米能级的相对距离大于偏压值时 。

We present the electronic structures and the basic properties of the first transition metal phthalocyanines ( Pc) as well as their simulated STM images obtained by using the first - principles method. The simulated STM images show submolecular structures and reproduce the main features of the experimental images. The results show that the valence configuration of the metal ion has a strong influence on the STM images. At small tip bias voltage, unlike ScPc, NiPc and CuPc, wherein the central metal ions appear as a hole in the molecular images, the metal ion in other MPcs STM images are the highlighted bumps. Moreover, we have studied the dependentce of the STM images of ScPc and NiPc molecules on the bias voltage, and predicted that the central metal ions in ScPc and NiPc images appear as bumps when the tip bias voltage is larger than -0.8V and 0.7V, respectively. The simulated STM images are interpreted as that the ScPc, NiPc and CuPc molecules have no significant d(z)(2) character near the Fermi level, while the TiPc, VPc, CrPc, MnPc, FePc and CoPc systems have.