Insights into the structures, energies and electronic properties of nesquehonite surfaces by first-principles calculations

Abstract

By using the first-principles calculations, the structure, energies and electronic properties of four commonly exposed surfaces for the nesquehonite crystal were investigated. The needle-like nesquehonite whisker is well developed with smooth side faces and irregular hexagonal end faces. Surface energy results indicate that the (101) surface is the most stable surface and corresponds to the side face. The density of dangling bond has a positive relationship with surface energy and the (101) surface has the least dangling bonds. In terms of relaxed surface energy, the order of relaxed surfaces is (101) < (200)-H < (301) < (200)-M < (004). During surface relaxation, the changes in the length of Mg-O bonds and hydrogen bonds contribute to generating a more stable surface with a lower surface energy. The PDOS (partial density of states) of these surfaces are mainly dominated by Mg and O atoms. A small peak value is found in the PDOS of (101) and (301) surfaces, which have less exposed Mg-O bonds. Electron transfer causes changes in the length of Mg-O bonds. A more active surface will obtain a larger value of transferred electrons during surface relaxation.