Lateral semiconductor/semiconductor heterostructures made up of two-dimensional (2D) monolayer or few-layer materials provide new opportunities for 2D devices. Herein, we propose four lateral heterostructures constructed by phosphorene-like monolayer group-IV monochalcogenides, including GeS/GeSe, SnS/GeSe, SnSe/GeS and GeS/SnS. Using first-principles calculations, we investigated the energetics and electronic properties of these lateral heterostructures. The band structures and formation energies from supercell calculations demonstrate that these heterostructures retain semiconducting behavior and can be easily synthesized in the laboratory. The band offsets of monolayer, bilayer and trilayer heterojunctions at the Anderson limit are calculated from the valence/conduction band edges with respect to the vacuum energy level for each individual component. Among them, some heterostructures belong to type II band alignment and are promising for a high-efficiency solar cell.

We employ a noncollinear implementation of density functional theory (DFT) including spin–orbit coupling (SOC) interaction to calculate the magnetic properties of Irn (n = 2–5) clusters. The impact of the magnetic anisotropy on the geometric structures and magnetic properties has been analyzed. SOC leads to formation of large orbital moment and a mixing of different spin states, but does not affect the relative stability of different structural isomers for a given cluster. In order to measure the SOC effect, we further define the spin–orbit energy (Eso) and compute the exact values. Magnetic anisotropy energies (MAEs) obtained from DFT calculations are further supported by the results of torque approach. We find that MAEs of Ir2 and Ir3 in ground state configurations are 40.6 and 28.5 meV respectively, while the MAE decreases to 9 meV for Ir4. For Ir5, MAE for its ground state structure increases to 38.3 meV.

Natural gas mixtures are inclusion compounds composed of major light hydrocarbon gaseous molecules (CH4, C2H6, C3H6, and C3H8). Previous ab initio calculations were mainly limited by the cluster models. For the first time, we report first-principles calculations on the stability and vibrational properties of the gas molecules inside the crystalline lattice of type II clathrate. In accordance with our calculations, the larger the size of guest molecule, the more stable the clathrate hydrate for small-sized alkane guest molecules (CnHm, n ≤ 3, m ≤ 8). The interaction energy per guest molecule gradually increases as the number of guest molecules increase for both sII pure and sII mixed hydrates. In addition, the vibrational frequencies of guest molecules trapped in sII hydrate are also simulated. The C–C stretching frequency shows a blue shift as the amount of guest molecules increase. Our theoretical results prove to be valuable insight for identifying the types of guest molecules from experimental spectroscopic data.

Using first-principle calculations at B97-D/6-311++G(2d,2p) level, we systematically explore the gas capacity of five standard water cavities (512, 435663, 51262, 51264, and 51268) in clathrate hydrate and study the inclusion complexes to infer general trends in vibrational frequencies of guest molecules as a function of cage size and number of guest molecules. In addition, the Raman spectra of hydrates from CO2/CH4 gases are simulated. From our calculations, the maximum cage occupancy of the five considered cages (512, 435663, 51262, 51264, and 51268) is one, one, two, three, and seven for both CH4 and CO2 guest molecules, respectively. Meanwhile, the optimum cage occupancy are one, one, one, two, and four for CO2 molecules and one, one, two, three, and five for CH4 molecules, respectively. Both the C–H stretching frequency of CH4 and the C–O stretching frequency of CO2 gradually decrease as size of the water cages increases. Meanwhile, the C–H stretching frequency gradually increases as the amount of CH4 molecules in the water cavity (e.g., 51268) increases.

Studies on the stereo-dynamical of the reaction S(1D) + H2 and its isotopic variants have been performed using quasi-classical trajectory (QCT) method on a globally smooth ab initio potential surface of the 1A′ state which is produced by Ho et al. [11] at the collision energy of 0–22.0 kcal/mol. We present the reaction cross section as a function of collision energy, which show satisfactory agreement in the reaction cross section of Ho et al. [11]. Four polarization dependent generalized differential cross-sections (PDDCSs) have been calculated in the center-of-mass frame. Comparisons of the distributions P(θr), P(φr) and P(θr,φr), which denotes respectively the distribution of angles between k and j′, the distribution of dihedral angle denoting k–k′–j′ correlation and the angular distribution of product rotational vectors in the form of polar plots, are given for the isotopic variants and collision energies.Graphical abstractHighlights► The S(1D) + H2 and its isotopic variants have been studied. ► Isotope effect about chemical reaction stereo-dynamics has been calculated. ► The influence of the collision energy is demonstrated.

Lateral semiconductor/semiconductor heterostructures made up of two-dimensional (2D) monolayer or few-layer materials provide new opportunities for 2D devices. Herein, we propose four lateral heterostructures constructed by phosphorene-like monolayer group-IV monochalcogenides, including GeS/GeSe, SnS/GeSe, SnSe/GeS and GeS/SnS. Using first-principles calculations, we investigated the energetics and electronic properties of these lateral heterostructures. The band structures and formation energies from supercell calculations demonstrate that these heterostructures retain semiconducting behavior and can be easily synthesized in the laboratory. The band offsets of monolayer, bilayer and trilayer heterojunctions at the Anderson limit are calculated from the valence/conduction band edges with respect to the vacuum energy level for each individual component. Among them, some heterostructures belong to type II band alignment and are promising for a high-efficiency solar cell.