title: Intriguing structures and magic sizes of heavy noble metal nanoclusters around size 55 governed by relativistic effect and covalent bonding.
abstract: Nanoclusters usually display exotic physical and chemical properties due to their intriguing geometric structures in contrast to their bulk counterparts. By means of first-principles calculations within density functional theory, we find that heavy noble metal PtN nanoclusters around the size N = 55 begin to prefer an open configuration, rather than previously reported close-packed icosahedron or core-shell structures. Particularly, for PtN, the widely supposed icosahedronal magic cluster is changed to a three-atomic-layered structure with D6h symmetry, which can be well addressed by our recently established generalized Wulff construction principle (GWCP). However, the magic number of PtN clusters around 55 is shifted to a new odd number of 57. The high symmetric three-layered Pt57 motif is mainly stabilized by the enhanced covalent bonding contributed by both spin-orbital coupling effect and the open d orbital (5d(9)6s(1)) of Pt, which result in a delicate balance between the enhanced Pt-Pt covalent bonding of the interlayers and negligible d dangling bonds on the cluster edges. These findings about PtN clusters are also applicable to IrN clusters, but qualitatively different from their earlier neighboring element Os and their later neighboring element Au. The magic numbers for Os and Au are even, being 56 and 58, respectively. The findings of the new odd magic number 57 are the important supplementary of the recently established GWCP.
authors.affiliation: International Laboratory for Quantum Functional Materials of Henan and School of Physics and Engineering, Zhengzhou University, Zhengzhou 450001, China.
authors.forename: X J
authors.initials: XJ
authors.lastname: Zhao
authors.affiliation: International Laboratory for Quantum Functional Materials of Henan and School of Physics and Engineering, Zhengzhou University, Zhengzhou 450001, China.
authors.forename: X L
authors.initials: XL
authors.lastname: Xue
authors.affiliation: International Laboratory for Quantum Functional Materials of Henan and School of Physics and Engineering, Zhengzhou University, Zhengzhou 450001, China.
authors.forename: Z X
authors.initials: ZX
authors.lastname: Guo
authors.affiliation: International Laboratory for Quantum Functional Materials of Henan and School of Physics and Engineering, Zhengzhou University, Zhengzhou 450001, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Jia
authors.affiliation: International Laboratory for Quantum Functional Materials of Henan and School of Physics and Engineering, Zhengzhou University, Zhengzhou 450001, China.
authors.forename: S F
authors.initials: SF
authors.lastname: Li
authors.affiliation: ICQD, Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China.
authors.forename: Zhenyu
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA.
authors.forename: Y F
authors.initials: YF
authors.lastname: Gao