Dangling bonds in hydroxylated and aminated nanodiamonds: Application of the global optimization algorithm

Abstract

The geometric configuration of dangling bonds (DBs) – one of the most abundant paramagnetic defects in nanodiamonds (NDs) – is investigated by applying the global optimization algorithm (GOAT). A total of more than five million geometry optimization runs are carried out to search for the lowest-energy conformers of DBs introduced into hydroxylated and aminated NDs. An analysis of over 3,000 electronic g-tensor calculations performed for the obtained structures shows that only three unique DB types are present in octahedrally shaped C₃₅(OH)₃₆ and C₃₅(NH₂)₃₆ nanoparticles, enabling future studies on similar NDs with fully functionalized surfaces to consider a relatively small number of DBs and thereby save computational time and resources. It is also revealed that the arithmetically averaged isotropic g-shifts from the geometries of the standard optimization agree well with the GOAT results, although the behaviour of individual DBs is not properly captured.