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Electronic surface error in the Si interstitial formation energy Ann E. Mattsson,1,* Ryan R. Wixom,2, and Rickard Armiento3,
 

Summary: Electronic surface error in the Si interstitial formation energy
Ann E. Mattsson,1,* Ryan R. Wixom,2, and Rickard Armiento3,
1Multiscale Dynamic Materials Modeling MS 1322, Sandia National Laboratories, Albuquerque, New Mexico 87185-1322, USA
2Energetics Characterization MS 1445, Sandia National Laboratories, Albuquerque, New Mexico 87185-1455, USA
3
Physics Institute, University of Bayreuth, D-95440 Bayreuth, Germany
Received 7 March 2007; revised manuscript received 29 February 2008; published 25 April 2008
The results for Si interstitial formation energies differ substantially if calculated with quantum Monte Carlo
QMC or density functional theory DFT techniques. In fact, not even DFT results using different exchange-
correlation functionals agree well for these energies. We carefully quantify the differences between the DFT
results by accurate calculations with large supercells. A similar discrepancy for vacancy formation energies in
metals has previously been resolved by introducing the concept of an "electronic surface error," and this view
is adopted and shown relevant also for the present DFT results for interstitials in semiconductors. The origin of
the surface error for the Si interstitial is explained by careful examination of the electron density. A postcor-
rection for the surface error brings all the results obtained with the tested functionals close to the results of the
AM05 functional. However, it remains an important puzzle that while the surface error correction aligns the
DFT results, they are still in large disagreement with QMC results.
DOI: 10.1103/PhysRevB.77.155211 PACS number s : 71.15.Mb, 61.72.J , 73.90. f
I. INTRODUCTION
The importance of silicon in our technology-based society

  

Source: Armiento, Rickard - Department of Physics, Royal Institute of Technology (KTH)

 

Collections: Materials Science; Physics