Graphite and Hexagonal Boron-Nitride have the Same Interlayer Distance. Why?

Graphite and hexagonal boron nitride (<i>h</i>-BN) are two prominent members of the family of layered materials possessing a hexagonal lattice structure. While graphite has nonpolar homonuclear C–C intralayer bonds, <i>h</i>-BN presents highly polar B–N bonds resulting in different optimal stacking modes of the two materials in the bulk form. Furthermore, the static polarizabilities of the constituent atoms considerably differ from each other, suggesting large differences in the dispersive component of the interlayer bonding. Despite these major differences, both materials present practically identical interlayer distances. To understand this finding, a comparative study of the nature of the interlayer bonding in both materials is presented. A full lattice sum of the interactions between the partially charged atomic centers in <i>h</i>-BN results in vanishingly small contributions to the interlayer binding energy. Higher order electrostatic multipoles, exchange, and short-range correlation Kohn–Sham contributions are found to be very similar in both materials and to almost completely cancel out by the kinetic energy term, which partly represents the effects of Pauli repulsions, at physically relevant interlayer distances, resulting in a marginal effective contribution to the interlayer binding. Further analysis of the dispersive energy term reveals that despite the large differences in the individual atomic polarizabilities, the heteroatomic B–N C₆ coefficient is very similar to the homoatomic C–C coefficient in the hexagonal bulk form, resulting in very similar dispersive contribution to the interlayer binding. The overall binding energy curves of both materials are thus very similar, predicting practically the same interlayer distance and very similar binding energies. The conclusions drawn here regarding the role of electrostatic interactions between partially charged atomic centers for the interlayer binding of <i>h</i>-BN are of a general nature and are expected to hold true for many other polar layered systems

Controlling the Electronic Properties of Nanodiamonds via Surface Chemical Functionalization: A DFT Study

The electronic properties of chemically functionalized nanodiamonds are studied using density functional theory calculations. HOMO–LUMO gaps and relative stabilities are calculated for different surface functionalization schemes and diamond nanocrystal morphologies. The effects of chemical decoration on the size and nature of the HOMO–LUMO gap of the various systems considered are discussed in detail. We conclude that surface chemical functionalization has the potential to become an accessible route for controlling the electronic properties of nanodiamonds

Controlling the Electronic Properties of Nanodiamonds via Surface Chemical Functionalization: A DFT Study

The electronic properties of chemically functionalized nanodiamonds are studied using density functional theory calculations. HOMO–LUMO gaps and relative stabilities are calculated for different surface functionalization schemes and diamond nanocrystal morphologies. The effects of chemical decoration on the size and nature of the HOMO–LUMO gap of the various systems considered are discussed in detail. We conclude that surface chemical functionalization has the potential to become an accessible route for controlling the electronic properties of nanodiamonds

Effects of Edge Oxidation on the Structural, Electronic, and Magnetic Properties of Zigzag Boron Nitride Nanoribbons

The effects of edge chemistry on the relative stability and electronic properties of zigzag boron nitride nanoribbons (ZBNNRs) are investigated. Among all functional groups considered, fully hydroxylated ZBNNRs are found to be the most energetically stable. When an in-plane external electric field is applied perpendicular to the axis of both hydrogenated and hydroxylated ZBNNRs, a spin-polarized half-metallic state is induced, whose character is different than that predicted for zigzag graphene nanoribbons. The onset field for achieving the half-metallic state is found to mainly depend on the width of the ribbon. Our results indicate that edge functionalization of ZBNNRs may open the way for the design of new nanoelectronic and nanospintronic devices

Registry-Dependent Peeling of Layered Material Interfaces: The Case of Graphene Nanoribbons on Hexagonal Boron Nitride

Peeling of layered materials from supporting substrates, which is central for exfoliation and transfer processes, is found to be dominated by lattice commensurability effects in both low and high velocity limits. For a graphene nanoribbon atop a hexagonal boron nitride surface, the microscopic peeling behavior ranges from stick-slip, through smooth-sliding, to pure peeling regimes, depending on the relative orientation of the contacting surfaces and the peeling angle. The underlying mechanisms stem from the intimate relation between interfacial registry, interlayer interactions, and friction. This, in turn, allows for devising simple models for extracting the interfacial adhesion energy from the peeling force traces

Registry-Dependent Peeling of Layered Material Interfaces: The Case of Graphene Nanoribbons on Hexagonal Boron Nitride

Peeling of layered materials from supporting substrates, which is central for exfoliation and transfer processes, is found to be dominated by lattice commensurability effects in both low and high velocity limits. For a graphene nanoribbon atop a hexagonal boron nitride surface, the microscopic peeling behavior ranges from stick-slip, through smooth-sliding, to pure peeling regimes, depending on the relative orientation of the contacting surfaces and the peeling angle. The underlying mechanisms stem from the intimate relation between interfacial registry, interlayer interactions, and friction. This, in turn, allows for devising simple models for extracting the interfacial adhesion energy from the peeling force traces

Numerical Approach to Nonequilibrium Quantum Thermodynamics: Nonperturbative Treatment of the Driven Resonant Level Model Based on the Driven Liouville von-Neumann Formalism

Nonequilibrium thermodynamics of the driven resonant-level model is studied using numerical simulations based on the driven Liouville von-Neumann formalism. The approach is first validated against recently obtained analytical results for quasistatic level shifts and the corresponding first-order corrections. The numerical approach is then used to study far-from-equilibrium thermodynamic properties of the system under finite level shift rates. The proposed methodology allows the study of unexplored nonequilibrium thermodynamic regimes in open quantum systems

Registry-Dependent Peeling of Layered Material Interfaces: The Case of Graphene Nanoribbons on Hexagonal Boron Nitride

Peeling of layered materials from supporting substrates, which is central for exfoliation and transfer processes, is found to be dominated by lattice commensurability effects in both low and high velocity limits. For a graphene nanoribbon atop a hexagonal boron nitride surface, the microscopic peeling behavior ranges from stick-slip, through smooth-sliding, to pure peeling regimes, depending on the relative orientation of the contacting surfaces and the peeling angle. The underlying mechanisms stem from the intimate relation between interfacial registry, interlayer interactions, and friction. This, in turn, allows for devising simple models for extracting the interfacial adhesion energy from the peeling force traces

Nanotube Slidetronics

One-dimensional slidetronics is predicted for double-walled boron-nitride nanotubes. Local electrostatic polarization patterns along the body of the nanotube are found to be determined by the nature of the two nanotube walls, their relative configuration, and circumferential faceting modulation during coaxial interwall sliding. By careful choice of chiral indices, chiral polarization patterns can emerge that spiral around the nanotube circumference. The potential usage of the discovered slidetronic effect for low-dimensional nanogenerators is briefly discussed