CoPc adsorption on Cu(111): Origin of the C4 to C2 symmetry reduction
CoPc adsorption on Cu(111): Origin of the C4 to C2 symmetry reduction
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DOI：
10.1063/1.3502682
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发表时间：
2010-10-21
影响因子：
4.4
通讯作者：
Tang, Hao
中科院分区：
文献类型：
--
作者：
Cuadrado, Ramon;Cerda, Jorge I.;Tang, Hao
酞菁（Pc）在各种表面上的吸附最近被报道导致扫描隧道显微镜（STM）图像中从C4到C2的对称性降低。降低对称性的可能起源涉及分子的电子结构或几何变形。在这里，还原的起源澄清从全面的理论研究CoPc吸附在Cu（111）表面沿着与STM实验数据。总能量计算使用不同的计划交换相关能量和STM模拟与实验数据进行比较。我们发现，只有当货车德瓦耳斯修正包括到形式主义的对称性约化再现。它是由沿着两个垂直的分子轴的沿着变形引起的，其中一个靠近表面约0.2埃。电子结构分析揭示了（i）CoPc与Cu（111）表面态相互作用的相关性，以及（ii）dI/dV图中的分子内特征清楚地将Co衍生态与其余Pc态区分开来。(C)2010年美国物理学会。[doi：10.1063/1.3502682]
adsorption of phthalocyanines (Pc) to various surfaces has recently been reported to lead to a lowering of symmetry from C4 to C2 in scanning tunneling microscope (STM) images. Possible origins of the reduced symmetry involve the electronic structure or geometric deformation of the molecules. Here, the origin of the reduction is clarified from a comprehensive theoretical study of CoPc adsorbed on the Cu(111) surface along with the experimental STM data. Total energy calculations using different schemes for the exchange-correlation energy and STM simulations are compared against experimental data. We find that the symmetry reduction is only reproduced when van der Waals corrections are included into the formalism. It is caused by a deformation along the two perpendicular molecular axes, one of them coming closer to the surface by around 0.2 angstrom. An electronic structure analysis reveals (i) the relevance of the CoPc interaction with the Cu(111) surface state and (ii) that intramolecular features in dI/dV maps clearly discriminate a Co-derived state from the rest of the Pc states. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3502682]