摘要
The adsorption properties of a magnesium porphyrin(MgP)molecule on Au(111)surface covered with up to three lay-ers of sodium chloride(NaCl)were investigated by means of first-principles calculations.The most stable adsorption configuration of MgP on the NaCl/Au(111)heterosurfaces was found to be at the Cl-top site with a 20°angle between the[110]lattice direction of NaCl and the Mg–N bond of the molecule.Compared with MgP molecule adsorbed on bare Au(111),the inclusion of NaCl lay-ers can lead to a significant decrease in the adsorption energy of the MgP molecule.The exis-tence of NaCl layers also reduced the charge transfer between the molecule and the surface.For heterosurfaces with two or three monolayers of NaCl,the charge transfer was almost com-pletely suppressed.The obtained partial density of states(PDOS)showed that hybridization between the electronic structures of the adsorbed MgP molecule and the metal surface can be significantly suppressed when NaCl layers were added.For the heterosurface with three lay-ers of NaCl,the PDOS around the Fermi level was almost identical with that of the free molecule,suggesting the electronic structure of the MgP molecule was nicely preserved.Influ-ence of the NaCl layers on the electronic structure of the MgP molecule was mainly found for molecular orbitals(MOs)away from the Fermi level as a result of the large band gap of the NaCl layers.
本文基于第一性原理计算研究了镁卟啉(MgP)分子在由1到3层氯化钠(NaCl)覆盖的Au(111)表面的吸附行为.计算结果表明:MgP在NaCl/Au(111)异质表面的最稳定吸附构型,处于CI原子顶位,且分子中Mg-N键与NaCl[1I0]晶向呈20°夹角,与直接吸附在Au(111)表面的情况相比,NaCl的引入可使MgP分子的吸附能显著降低,且可抑制MgP与金属衬底之间的电荷转移;当NaCl层数达到2~3层时,MgP与衬底间的电荷转移几乎被完全抑制.通过分析计算得到的部分态密度发现,NaCl解耦层的存在能够显著减弱吸附分子与金属表面电子态的杂化效应;对于包含3层NaCl的异质表面,MgP分子在费米能级附近的部分态密度与自由分子几乎完全一致,表明吸附分子的本征电子结构得到了很好的保留,这主要是由于NaCl的带隙很宽,仅对远离费米能级的分子轨道产生显著的影响.
基金
supported by the National Natural Science Foundation of China(No.22373084,No.62201494)
Hebei Natural Science Foundation(B2022203007)
the Cultivation Project for Basic Research and Innovation of Yanshan University(2024LGZD002).
