Fundamental properties of alkali-intercalated bilayer graphene nanoribbons.

Along with the inherent remarkable properties of graphene, adatom-intercalated graphene-related systems are expected to exhibit tunable electronic properties. The metal-based atoms could facilitate multi-orbital hybridizations with the out-of-plane π-bondings on the carbon honeycomb lattice, which dominate the fundamental properties of chemisorption systems. In this work, using first-principles calculations, the feature-rich properties of alkali-metal intercalated graphene nanoribbons (GNRs) are investigated, including edge passivation, stacking configurations, intercalation sites, stability, charge density distribution, magnetic configuration, and electronic properties.

Compression-induced hexa-to-tetra phase transition of confined germanene.

Via molecular dynamics (MD) simulations we find the existence of the new allotrope of two-dimensional (2D) germanene, i.e. 2D tetra-germanene (tetra-Ge) which contains entirely tetragons.

Study of LiCoO/LiLaZrO:Ta Interface Degradation in All-Solid-State Lithium Batteries.

The garnet-type LiLaZrO (LLZO) ceramic solid electrolyte combines high Li-ion conductivity at room temperature with high chemical stability. Several all-solid-state Li batteries featuring the LLZO electrolyte and the LiCoO (LCO) or LiCoO-LLZO composite cathode were demonstrated. However, all batteries exhibit rapid capacity fading during cycling, which is often attributed to the formation of cracks due to volume expansion and the contraction of LCO.

Diversified Phenomena in Metal- and Transition-Metal-Adsorbed Graphene Nanoribbons.

Adatom-adsorbed graphene nanoribbons (GNRs) have gained much attention owing to the tunable electronic and magnetic properties. The metal (Bi, Al)/transition metal (Ti, Fe, Co, Ni) atoms could provide various outermost orbitals for the multi-orbital hybridizations with the out-of-plane π bondings on the carbon honeycomb lattice, which dominate the fundamental properties of chemisorption systems. In this study, the significant similarities and differences among Bi-/Al-/Ti-/Fe-/Co-/Ni-adsorbed GNRs are thoroughly investigated by using the first-principles calculations.

Orbital-hybridization-created optical excitations in LiGeO.

The three-dimensional ternary LiGeO compound presents various unusual essential properties. The main features are thoroughly explored from the first-principles calculations. The concise pictures, the critical orbital hybridizations in Li-O and Ge-O bonds, are clearly examined through the optimal geometric structure, the atom-dominated electronic energy spectrum, the spatial charge densities, the atom and orbital-decomposed van Hove singularities, and the strong optical responses.

Rich -type-doping phenomena in boron-substituted silicene systems.

The essential properties of monolayer silicene greatly enriched by boron substitutions are thoroughly explored through first-principles calculations. Delicate analyses are conducted on the highly non-uniform Moire superlattices, atom-dominated band structures, charge density distributions and atom- and orbital-decomposed van Hove singularities. The hybridized 2 -3 and [2s, 2 , 2 ]-[3s, 3 , 3 ] bondings, with orthogonal relations, are obtained from the developed theoretical framework.

Unusual features of nitrogen substitutions in silicene.

The quasiparticle properties resulting from charge and spin are clearly identified in nitrogen-substituted silicenes, for which a theoretical framework is successfully developed from first-principles calculations. Such systems create extremely non-uniform chemical and physical environments through the distribution of the guest atoms. They present unusual geometric, electronic, and magnetic properties, which can be identified from the optimal honeycomb lattices, the atom- and spin-dominated energy spectra, the spatial charge density distributions, and the atom-, orbital- and spin-projected van Hove singularities [the net magnetic moments].

Essential geometric and electronic properties in stage- graphite alkali-metal-intercalation compounds.

The rich and unique properties of the stage- graphite alkali-metal-intercalation compounds are fully investigated by first-principles calculations. According to the main features, the lithium and non-lithium (Na, K, Rb, Cs) systems are quite different from each other in stacking configurations, intercalant alkali-metal-atom concentrations, free conduction electron densities, atom-dominated and (carbon, alkali metal)-co-dominated energy bands, and interlayer charge density distributions. The close relations between the alkali-metal-doped metallic behaviors and the geometric symmetries are clarified through the interlayer atomic interactions.

First-principles studies of electronic properties in lithium metasilicate (LiSiO).

Lithium metasilicate (LiSiO), which could serve as the electrolyte material in Li-based batteries, exhibits unique lattice symmetry (an orthorhombic crystal), valence and conduction bands, charge density distribution, and van Hove singularities. Delicate analyses, based on reliable first-principles calculations, are utilized to identify the critical multi-orbital hybridizations in Li-O and Si-O bonds, 2s-(2s, 2p , 2p , 2p ) and (3s, 3p , 3p , 3p )-(2s, 2p , 2p , 2p ), respectively. This system shows a huge indirect gap of 5.

Fundamental Properties of Metal-Adsorbed Silicene: A DFT Study.

Sodium, magnesium, and aluminum adatoms, which possess one, two, and three valence electrons, respectively, in terms of 3s, 3s, and (3s, 3p) orbitals, are very suitable for helping us understand adsorption-induced diverse phenomena. In this work, the revealing properties of metal (Na/Mg/Al)-adsorbed graphene systems are investigated by means of the first-principles method. The single- and double-sided chemisorption cases, the various adatom concentrations, the hollow/top/valley/bridge sites, and the buckled structures are taken into account.

Effect of 1,3-Propane Sultone on the Formation of Solid Electrolyte Interphase at Li-Ion Battery Anode Surface: A First-Principles Study.

Density functional theory is applied to investigate the reductive reactions of reductive-type additive, 1,3-propane sultone (PS), on the formation of solid electrolyte interphase (SEI) near the lithium-ion battery anode surface. Different from the studies that mostly focus on the reduction dissociation of a specific molecule, we adopt an iterative method that systematically considered most possible reactants from the environment in every round of the reaction. The thermodynamically favorable reaction in each round was chosen.

Concentration-Diversified Magnetic and Electronic Properties of Halogen-Adsorbed Silicene.

Diverse magnetic and electronic properties of halogen-adsorbed silicene are investigated by the first-principle theoretical framework, including the adatom-diversified geometric structures, atom-dominated energy bands, spatial spin density distributions, spatial charge density distributions and its variations, and orbital-projected density of states. Also, such physical quantities are sufficient to identify similar and different features in the double-side and single-side adsorptions. The former belongs to the concentration-depended finite gap semiconductors or p-type metals, while the latter display the valence energy bands with/without spin-splitting intersecting with the Fermi level.

Fundamental Properties of Transition-Metals-Adsorbed Graphene.

The revealing properties of transition metal (T)-doped graphene systems are investigated with the use of the first-principles method. The detailed calculations cover the bond length, position and height of adatoms, binding energy, atom-dominated band structure, adatom-induced free carrier density as well as energy gap, spin-density distributions, spatial charge distribution, and atom-, orbital- and spin-projected density-of-states (DOS). The magnetic configurations are clearly identified from the total magnetic moments, spin-split energy bands, spin-density distributions and spin-decomposed DOS.

Diverse Electronic and Magnetic Properties of Chlorination-Related Graphene Nanoribbons.

The dramatic changes in electronic and magnetic properties are investigated using the first-principles calculations for halogen(X: Cl, Br, I, At)-adsorbed graphene nanoribbons. The rich and unique features are clearly revealed in the atoms-dominated electronic band structures, spin arrangement/magnetic moment, spatial charge distribution, and orbital- and spin-projected density of states. Halogen adsorptions can create the non-magnetic, ferromagnetic or anti-ferromagnetic metals, being mainly determined by concentrations and edge structures.

Coverage-dependent essential properties of halogenated graphene: A DFT study.

The significant halogenation effects on the essential properties of graphene are investigated by the first-principles method. The geometric structures, electronic properties, and magnetic configurations are greatly diversified under the various halogen adsorptions. Fluorination, with the strong multi-orbital chemical bondings, can create the buckled graphene structure, while the other halogenations do not change the planar s bonding in the presence of single-orbital hybridization.

Fluorination-enriched electronic and magnetic properties in graphene nanoribbons.

The feature-rich electronic and magnetic properties of fluorine-doped graphene nanoribbons are investigated by the first-principles calculations. They arise from the cooperative or competitive relations among the significant chemical bonds, finite-size quantum confinement and edge structure. There exist C-C, C-F, and F-F bonds with multi-orbital hybridizations.

Chemical bonding-induced rich electronic properties of oxygen adsorbed few-layer graphenes.

The electronic properties of graphene oxides enriched by strong chemical bonding are investigated using first-principles calculations. They are very sensitive to the changes in the number of graphene layers, stacking configuration, and distribution of oxygen. The feature-rich electronic structures exhibit destruction or distortion of the Dirac cone, opening of a band gap, anisotropic energy dispersions, O- and (C,O)-dominated energy dispersions, and extra critical points.

H-Si bonding-induced unusual electronic properties of silicene: a method to identify hydrogen concentration.

Hydrogenated silicenes possess peculiar properties owing to the strong H-Si bonds, as revealed by an investigation using first principles calculations. Various charge distributions, bond lengths, energy bands, and densities of states strongly depend on different hydrogen configurations and concentrations. The competition between strong H-Si bonds and weak sp(3) hybridization dominate the electronic properties.