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Title: Electronic structure and surface properties of MgB 2 (0001) upon oxygen adsorption [Electronic structure and surface properties of MgB2: oxygen adsorption on MgB2(0001)]

Here, we use density-functional theory to investigate the bulk and surface properties of MgB 2. The unique bonding structure of MgB 2 is investigated by Bader's atoms-in-molecules, charge density difference, and occupancy projected band structure analyses. Oxygen adsorption on the charge-depleted surfaces of MgB 2 is studied by a surface potential energy mapping method, reporting a complete map including low-symmetry binding sites. The B-terminated MgB 2(0001) demonstrates reconstruction of the graphenelike B layer, and the reconstructed geometry exposes a threefold site of the subsurface Mg, making it accessible from the surface. Detailed reconstruction mechanisms are studied by simulated annealing method based on ab initio molecular dynamics and nudged elastic band calculations. The surface clustering of B atoms significantly modifies the B 2p states to occupy low energy valence states. The present paper emphasizes that a thorough understanding of the surface phase may explain an apparent inconsistency in the experimental surface characterization of MgB 2. Furthermore, these results suggest that the surface passivation can be an important technical challenge when it comes to development of a superconducting device using MgB 2.
Authors:
 [1] ;  [2] ;  [3] ;  [2]
  1. Purdue Univ., West Lafayette, IN (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  3. Purdue Univ., West Lafayette, IN (United States)
Publication Date:
Report Number(s):
LLNL-JRNL-736842
Journal ID: ISSN 2469-9950; PRBMDO; 888816
Grant/Contract Number:
AC52-07NA27344
Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 97; Journal Issue: 19; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 97 MATHEMATICS AND COMPUTING
OSTI Identifier:
1458711
Alternate Identifier(s):
OSTI ID: 1436828