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Register a new userFirst-principles studies of electronic properties in Lithium metasilicate (Li2SiO3)
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Lithium metasilicate (Li2SiO3) has attracted considerable interest as a promising electrolyte material for potential use in lithium batteries. However, its electronic properties are still not thoroughly understood. In this work, density functional theory calculations were adopted, our calculations find out that Li2SiO3 exhibits unique lattice symmetry (orthorhombic crystal), valence and conduction bands, charge density distribution, and van Hove singularities. Delicate analyses, the critical multi-orbital hybridizations in Li-O and Si-O bonds 2s- (2s, 2px, 2py, 2pz) and (3s, 3px, 3py, 3pz)- (2s, 2px, 2py, 2pz), respectively was identified. In particular, this system shows a huge indirect-gap of 5.077 eV. Therefore, there exist many strong covalent bonds, with obvious anisotropy and non-uniformity. On the other hand, the spin-dependent magnetic configurations are thoroughly absent. The theoretical framework could be generalized to explore the essential properties of cathode and anode materials of oxide compounds.
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The Li2SiO3 compound, a ternary electrolyte compound of Lithium-ion based batteries, exhibits unique geometric and band structures, an atom-dominated energy spectrum, charge densities distributions, atom and orbital-projected density of states, and strong optical responses. The state-of-the-art analysis, based on an ab-initio simulation, have successfully confirmed the concise physical/chemical picture and the orbital bonding in Li-O and Si-O bonds. Additionally, the unusual optical response behavior includes a large redshift of the onset frequency due to the extremely strong excitonic effect, the polarization of optical properties along three-directions, 22 optical excitations structures and the most prominent plasmon mode in terms of the dielectric functions, energy loss functions, absorption coefficients, and reflectance spectra. The close connections of electronic and optical properties can identify a specific orbital hybridization for each distinct excitation channel. The developed theoretical framework will be very appropriate for fully comprehending the diverse phenomena of cathode/electrolyte/anode materials in ion-based batteries.
As a storage material for Li-ion batteries, graphene/molybdenum disulfide (Gr/MoS2) composites have been intensively studied in experiments. But the relevant theoretical works from first-principles are lacking. In the current work, van-der-Waals-corrected density functional theory calculations are performed to investigate the interaction of Li in Gr/MoS2 composites. Three interesting features are revealed for the intercalated Gr/Li(n)/MoS2 composites (n = 1 to 9). One is the reason for large Li storage capacity of Gr/MoS2: due to the binding energies per Li atom increase with the increasing number of intercalated Li atoms. Secondly, the band gap opening of Gr is found, and the band gap is enlarged with the increasing number of intercalated Li atoms, up to 160 meV with nine Li; hence these results suggest an efficient way to tune the band gap of graphene. Thirdly, the Dirac cone of Gr always preserve for different number of ionic bonded Li atoms.
Structural, electronic, vibrational and dielectric properties of LaBGeO$_5$ with the stillwellite structure are determined based on textit{ab initio} density functional theory. The theoretically relaxed structure is found to agree well with the existing experimental data with a deviation of less than $0.2%$. Both the density of states and the electronic band structure are calculated, showing five distinct groups of valence bands. Furthermore, the Born effective charge, the dielectric permittivity tensors, and the vibrational frequencies at the center of the Brillouin zone are all obtained. Compared to existing model calculations, the vibrational frequencies are found in much better agreement with the published experimental infrared and Raman data, with absolute and relative rms values of 6.04 cm$^{-1}$, and $1.81%$, respectively. Consequently, numerical values for both the parallel and perpendicular components of the permittivity tensor are established as 3.55 and 3.71 (10.34 and 12.28), respectively, for the high-(low-)frequency limit.
SnSe monolayer with orthorhombic Pnma GeS structure is an important two-dimensional (2D) indirect band gap material at room temperature. Based on first-principles density functional theory calculations, we present systematic studies on the electronic and magnetic properties of X (X = Ga, In, As, Sb) atoms doped SnSe monolayer. The calculated electronic structures show that Ga-doped system maintains semiconducting property while In-doped SnSe monolayer is half-metal. The As- and Sb- doped SnSe systems present the characteristics of n-type semiconductor. Moreover, all considered substitutional doping cases induce magnetic ground states with the magnetic moment of 1{mu}B. In addition, the calculated formation energies also show that four types of doped systems are thermodynamic stable. These results provide a new route for the potential applications of doped SnSe monolayer in 2D photoelectronic and magnetic semiconductor devices.
In this work, we have presented a first principle simulation study on the electronic properties of MoS2/MX2/MoS2 (M=Mo or W; X=S or Se) trilayer heterostrcuture. We have investigated the effect of stacking configuration, bi-axial compressive and tensile strain on the electronic properties of the trilayer heterostructures. In our study, it is found that, under relaxed condition all the trilayer heterostructures at different stacking configurations show semiconducting nature. The nature of the bandgap however depends on the inserted TMDC monolayer between the top and bottom MoS2 layers and their stacking configurations. Like bilayer heterostructures, trilayer structures also show semiconducting to metal transition under the application of tensile strain. With increased tensile strain the conduction band minima shifts to K point in the brillouin zone and lowering of electron effective mass at conduction band minima is observed. The study on the projected density of states reveal that, the conduction band minima is mostly contributed by the MoS2 layers and states at the valance band maxima are contributed by the middle TMDC monolayer.
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