Nanodiamond Collective Electron States and their Localization

TL;DR

This study investigates the collective electron states in nanodiamond particles using quantum mechanical models and ab initio calculations, revealing their localization, types, and implications for intrinsic spins and magnetic properties.

Contribution

It introduces a new model describing collective electron states and their localization in nanodiamond, explaining free spins observed experimentally.

Findings

Identified three classes of collective electron states in nanodiamond.

Demonstrated subsurface localization of unpaired electrons due to surface compression.

Provided a quantum-mechanical explanation for intrinsic spin phenomena in nanodiamond.

Abstract

The existence and localization of collective electron states for nanodiamond particles were studied both by solving a one-particle one-dimensional Schr\"odinger equation in the Kronig-Penney potential and by ab initio computations of ground state wavefunctions of diamondoids C78H64, C123H100 and C211H140 at the DFT R-B3LYP/6-31G(d,p) level of theory. Three distinct classes of collective electron states have been found: collective bonding orbitals resembling the morphology of 3D-modulated particle in a box solutions; surface-localized non-bonding conductive Tamm states and subsurface-localized bonding states for non-uniformly compressed nanodiamond. Quantum-mechanical analysis shows that collective unpaired electrons are intrinsic to nanodiamond. Their subsurface localization is described in terms of surface compression arising from a self-consistency condition of the electron-nuclear wavefunction. Intrinsic spin existence is supposed to result from the collective and spread nature of subsurface orbitals, allowing spin-density fluctuation effects to become significant on this length scale. Suggested model allows to explain free spins of nanodiamond exhibited in experiments.