10.1021/acs.chemmater.6b03040.s001 Mikołaj Lewandowski Mikołaj Lewandowski Irene M. N. Groot Irene M. N. Groot Zhi-Hui Qin Zhi-Hui Qin Tomasz Ossowski Tomasz Ossowski Tomasz Pabisiak Tomasz Pabisiak Adam Kiejna Adam Kiejna Anastassia Pavlovska Anastassia Pavlovska Shamil Shaikhutdinov Shamil Shaikhutdinov Hans-Joachim Freund Hans-Joachim Freund Ernst Bauer Ernst Bauer Nanoscale Patterns on Polar Oxide Surfaces American Chemical Society 2016 electronegative regions Polar Oxide Surfaces Polar charge neutralization bulk termination surface energy nanoscale pattern formation Fe oxide surfaces theory-based calculations nanoscale pattern Several mechanisms surface terminations scanning tunneling microscopy spectroscopy results Nanoscale Patterns 2016-09-28 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Nanoscale_Patterns_on_Polar_Oxide_Surfaces/4029327 Polar ionic surfaces with bulk termination are inherently unstable because of their diverging electrostatic surface energy. Nevertheless, they are frequently observed in nature, mainly because of charge neutralization by adsorbates, but occur also under atomically clean conditions. Several mechanisms have been invoked to explain the stability of atomically clean polar surfaces, but the frequently observed periodic nanoscale pattern formation has not yet been explained. Here we propose that long-range interactions between alternating electropositive and electronegative regions of different surface terminations minimize the electrostatic energy of the surface and thus stabilize the nanoscale pattern. This is illustrated using the example of polar Fe oxide surfaces by combining scanning tunneling microscopy and spectroscopy results with results from density functional theory-based calculations and dipole–dipole interaction models.