Modeling of electronic and spin structure of single NV centers in nanostructured diamond: influence of nanodiamond surface

Abstract

Modeling of atomic structure and distribution of spin density for the NV center formed close to the surface (111) of nano-diamond has been carried out using quantum-chemical PM3 and DFT methods. The case is considered where the nitrogen atom of NV center is located in the near-surface atomic layer of a face (111). The relaxation of surface atoms relative to the initial position results in N atom to be shifted from the cluster center parallel to the <111> direction by 0.16Å, and C atoms belonging to the surface layer are also shifted parallel to the <111> direction to the center by 0.18Å. As this takes place, C-C and C-N distances between relaxed atoms decrease and a graphite-like structure is formed on a (111) crystal face. In the structure, the N atom and C atoms nearest to it lay practically in the same plane. The formed CN bond can be considered as one-and-a-half bond. It has been found that unlike the NV center in bulk diamond for which the spin density is located mainly on the carbon atoms, being nearest neighbors to the vacancy of the NV center, in the case of the NV center located in immediate proximity to the surface, there is a redistribution of spin density resulting in its major allocation in three C atoms, the nearest neighbors to the N atom, that form the first atomic layer of a surface (111) of nano-crystal.