A new silicene-like family of reconstructed surfaces on Si111 are discussed which appears to be a polymorph to the well know family of surface reconstructions best epitomized by the 7x7 surface. Several experimental features are discussed which lead to this new conclusion, as are several recently established limitations of density functional theory that may currently limit its ability to predict such 2-D surface structures. The atomic locations of the surface state charge densities from several Scanning Tunneling Spectroscopy studies provide the basis for this new structure which is supported by several previous measurements. The new structure appears to favor a faulted supercell honeycomb motif having a delocalized 2-D state that enables greater sp2 character. This top layer has an unusual periodic pi-orbital structure that also interdigitates with the terminal bulk 'dangling bonds' to create a 2-D pi-bonded structure. This new polymorphic structure resolves many long standing paradoxes of the 7x7 surface while its unusual bonding and structure may help better understand some silicenes as well as the behavior of other 2-D phases on 111 surfaces.
Majorana Zero Modes and Topological Nature in Bi2Ta3S6-family Superconductors
Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences（中国科学院物理研究所）；University of Chinese Academy of Sciences（中国科学院大学）；School of Mathematics and Physics, University of Science and Technology Beijing（北京科技大学数理学院）；Condensed Matter Physics Data Center, Chinese Academy of Sciences（中国科学院凝聚态物理数据中心）
