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Using the first-principles density functional theory calculations, we investigate the mechanical and electronic properties of biaxially strained graphitic carbon nitride (g-C3N4). The results show highly isotropic mechanical properties and large linear elasticity of g-C3N4. Moreover, both the Perdew-Burke-Ernzehof (PBE) and Heyd-Scuseria-Ernzerhof (HSE06) band gaps reach the maximum values at 10% strain. The bonding properties are analyzed based on the electronic localization function (ELF). In addition, the photon transition between band gap is weak, suggesting the monolayer g-C3N4 is not suitable for a solar cell material. Enough biaxial strain can induce the spin splitting of g-C3N4, and it is found that the spin-unrestricted band gap of g-C3N4 can be overestimated. This work provides valuable insights for designing the new elastic electronic and spintronic devices based on two-dimensional g-C3N4.

A method is developed in this study to determine the non-uniform input ground motion based on seismic records for the seismic analysis of high concrete face rockfill dams (CFRDs). The acceleration time histories recorded during the 2011 Tohoku earthquake at the Haga station is used as an example to determine the potential functions of the seismic waves. The recorded surface acceleration time history and calculated non-uniform input are then used to conduct analysis of the seismic response of the Gushui CFRD under both uniform and non-uniform input motions. Under the condition that the acceleration time histories on the surface of the free field are assumed to be the same for non-uniform and uniform seismic input, the seismic response of the CFRD under non-uniform input is found to be in general significantly smaller, while the local dynamic stresses around the edges of the concrete face slab are greater. The analysis results suggest that non-uniformity of the ground motion input has important effects on the seismic response of high CFRDs, and should be considered in the seismic design of CFRDs.

This paper presents a summary of the element test simulations (calibration simulations) submitted by 11 numerical simulation (prediction) teams that participated in the LEAP-2017 prediction exercise. A significant number of monotonic and cyclic triaxial (Vasko, An investigation into the behavior of Ottawa sand through monotonic and cyclic shear tests. Masters Thesis, The George Washington University, 2015; Vasko et al., LEAP-GWU-2015 Laboratory Tests. DesignSafe-CI, Dataset, 2018; El Ghoraiby et al., LEAP 2017: Soil characterization and element tests for Ottawa F65 sand. The George Washington University, Washington, DC, 2017; El Ghoraiby et al., LEAP-2017 GWU Laboratory Tests. DesignSafe-CI, Dataset, 2018; El Ghoraiby et al., Physical and mechanical properties of Ottawa F65 Sand. In B. Kutter et al. (Eds.), Model tests and numerical simulations of liquefaction and lateral spreading: LEAP-UCD-2017. New York: Springer, 2019) and direct simple shear tests (Bastidas, Ottawa F-65 Sand Characterization. PhD Dissertation, University of California, Davis, 2016) are available for Ottawa F-65 sand. The focus of this element test simulation exercise is to assess the performance of the constitutive models used by participating team in simulating the results of undrained stress-controlled cyclic triaxial tests on Ottawa F-65 sand for three different void ratios (El Ghoraiby et al., LEAP 2017: Soil characterization and element tests for Ottawa F65 sand. The George Washington University, Washington, DC, 2017; El Ghoraiby et al., LEAP-2017 GWU Laboratory Tests. DesignSafe-CI, Dataset, 2018; El Ghoraiby et al., Physical and mechanical properties of Ottawa F65 Sand. In B. Kutter et al. (Eds.), Model tests and numerical simulations of liquefaction and lateral spreading: LEAP-UCD-2017. New York: Springer, 2019). The simulated stress paths, stress strain responses, and liquefaction strength curves show that majority of the models used in this exercise are able to provide a reasonably good match to liquefaction strength curves for the highest void ratio (0.585) but the differences between the simulations and experiments become larger for the lower void ratios (0.542 and 0.515).

α-AsP monolayer is a two-dimensional (2D) black phosphorene-like material with potential applications in electronics and gas sensors due to ultra-high carrier mobility. Here, we investigate the gas sensing properties of nonmetal (Si and S) atoms doped α-AsP monolayer using the first-principles calculations based on the density functional theory (DFT-D2 method). The results show that the nonmetal doping can significantly improve selectivity and sensitivity toward NO2 compared with other interfering gas molecules. Especially, the S doped α-AsP monolayer possesses a high selectivity to NO2 with moderate adsorption energy of −0.82 eV, a high sensitivity with significant WF change of 0.39 eV and larger sensitivity value of 53.8 %. By analyzing the electron localization function (ELF) and electronic structure, the enhanced adsorption ability of the S doped α-AsP monolayer to NO2 is mainly determined by electrostatic interaction. In addition, adsorption behavior of NO2 on S doped α-AsP monolayer can be effectively affected by applying external strain and electric field, meaning that strain/electric field can be used as a controllable method for gas storage and release. Therefore, these results not only provide fundamental insights for nonmetal doped α-AsP monolayer as promising gas sensing material for NO2 detection, but also provide a theoretical guideline for designing high performance gas sensors based on 2D AsP.

In recent years, the discovery of ‘magic angle’ graphene has given new inspiration to the formation of heterojunctions. Similarly, the use of hexagonal boron nitride, known as white graphene, as a substrate for graphene devices has more aroused great interest in the graphene/hexagonal boron nitride heterostructure system. Based on the first principles method of density functional theory, the band structure, density of states, Mulliken population, and differential charge density of a tightly packed model of twisted graphene/hexagonal boron nitride/graphene sandwich structure have been studied. Through the establishment of heterostructure models twisted bilayer-graphene inserting hBN with different twisted angles, it was found that the band gap, Mulliken population, and charge density, exhibited specific evolution regulars with the rotation angle of the upper graphene, showing novel electronic properties and realizing metal–insulator phase transition. We find that the particular value of the twist angle at which the metal–insulator phase transition occurs and propose a rotational regulation mechanism with angular periodicity. Our results have guiding significance for the practical application of heterojunction electronic devices.

The effects of the pressure on the structural, electronic, magnetic and optical properties of the Zn0.75V0.25Te alloy have been investigated by density functional calculations. The ductile characteristic and the half-metallic feature of Zn0.75V0.25Te alloy under pressure are found. The band structures with a color scale indicating the contribution weights from V and Te + Zn atoms show that V element is dominant in the spin-up channel crossing the Fermi level but there is a band gap in the spin-down channel. The half-metallic feature of the Zn0.75V0.25Te alloy can be observed under the pressures of 0–4 GPa. It is discovered that the total moment of 3 μB/cell is contributed by the three 3d-electrons of V2+ ion. With increasing pressure, the spin-down band gap E g increases, while the static dielectric function e 1 ( 0 ) and static refractive index n ( 0 ) decrease, the peaks of the real part e 1 ( ω ) and imaginary part e 2 ( ω ) of the dielectric constant, the refractive index n ( ω ) , the extinction coefficient k ( ω ) and absorption coefficient α ( ω ) all show the blue shift character. The results provide useful theoretical guidance for the application of the Zn0.75V0.25Te alloy in optical detectors and spintronics devices under pressure.

In this study, the structural and electronic properties of CoX0.25S1.75 (X = F, Cl, or Br) were investigated based on spin-polarized first-principles calculations. S-F, S-Cl, and S-Br covalent bonds are not present in CoX0.25S1.75 (X = F, Cl, or Br). The generalized gradient approximation (GGA) + U and Heyd-Scuseria-Ernzerhof hybrid functional method may overestimate the spin-down band gap for CoS2. The results obtained for CoX0.25S1.75 (X = F, Cl, or Br) using the GGA method are expected to be more reasonable. Only the half-metal CoF0.25S1.75 can be used for spintronic applications and the metal CoX0.25S1.75 (X = Cl or Br) is more suitable for use in supercapacitors. The p-d hybridization between S and Co atoms in CoF0.25S1.75 is stronger compared with that in CoS2. The p-d hybridization between S(S-X) and Co atoms is stronger whereas that between S(S-S) and Co atoms is weaker in CoX0.25S1.75 (X = Cl or Br). Doping with F and Cl (Br) atoms in CoS2 induces new bands with less and more dispersion, respectively. In CoX0.25S1.75 (X = F or Cl), X atoms gain more electrons than S atoms and the charge density difference indicates that S atoms donate electrons to F and Cl atoms. However, in CoBr0.25S1.75, Br atoms gain fewer electrons than S atoms and there is almost no charge transfer between S and Br atoms.

The purpose of this study was to determine the diagnostic accuracy of serum inhibin B (INHB) as a predictor of the retrieval outcome of testicular haploid gametes (spermatids and testicular spermatozoa) in nonobstructive azoospermic men. Serum hormone levels, testicular volume, and histological evaluation were performed in 403 Chinese nonobstructive azoospermic men. Testicular haploid gamete was successfully retrieved in 213 of 403 patients (52.85%). The haploid gamete group always had higher INHB levels than the non-haploid gamete group. According to the receiver operating characteristic (ROC) curve analysis, INHB was a good predictor of testicular haploid gamete retrieval outcome in all patients (sensitivity: 77.93% and specificity: 91.58%) and patients with normal follicle-stimulating hormone (FSH; sensitivity: 88.52% and specificity: 70.83%). The area under the ROC curve (AUC) of INHB was similar to that of FSH in all patients or patients with normal FSH. In patients with elevated FSH, INHB was superior to FSH in predicting the presence of haploid gamete (AUC: 0.73 vs 0.55, P < 0.05), with a sensitivity of 60.00% and a specificity of 80.28%. It concluded that serum INHB as an effective marker for spermatogenesis was a significant predictor of testicular haploid gamete retrieval outcomes in nonobstructive azoospermic men. Especially, INHB is superior to FSH in predicting the presence of haploid gamete in the patients with elevated FSH.

Gravel–structure interfaces are involved in many large-scale geotechnical applications and play a vital role in the performance of soil–structure interaction systems. A large-scale simple-shear device was professionally developed and used to investigate three-dimensional (3-D) monotonic and cyclic shear behavior of a gravel–steel interface in two-way beeline, cross, and circular shear paths. The soil deformation was measured and was used to determine the interface thickness. The deforming and sliding displacements of the interface were quantified and separated from the total tangential displacement. Results show that the interface thickness is about 6–7 times the mean grain size, D50, independent of the normal stress and shear path. Under 3-D loading conditions, the shear stress vs. tangential displacement hysteretic response exhibits notably 3-D features. The interface becomes stiffer because of the hardening behavior of the gravel during cyclic shearing. The total normal displacement can be divided into irreversible and reversible components, which present different responses. The peak shear strength is mobilized when the interface dilatancy rate reaches the maximum at a sliding displacement of about 0.5D50, and behaves in an anisotropic manner caused by the shear orientation effect. The normal stress and shear paths have significant influences on the 3-D interface behavior.

The structural, electronic and magnetic properties in bulk and various (0 0 1) surfaces of X2CoIn (X = Ti, Zr) Heusler alloy have been investigated by spin-polarized first-principles calculations. The InIn termination is the most stable one and the XIn termination is the second only to InIn termination as the most stable surface, with high spin polarizations 65.2% and 62.3% for X = Ti (80.8% and 69.6% for X = Zr), respectively. The atomic partial density of states (APDOS) and atomic magnetic moments (AMMs) of atoms in the central layer of X2CoIn (0 0 1) surface accord well with those of the corresponding atoms in bulk X2CoIn structure. The half-metallic (HM) feature is destroyed by the surface states for all the five CoCo, XCo, XX, XIn and InIn terminations. The total magnetic moment is contributed by atoms in all layers for Ti2CoIn (0 0 1) surface while is mainly contributed by the atoms in the fourth to central layers (L4 to L9) for the ZrIn termination but is mainly contributed by the atoms in the sixth to central layers (L6 to L9) for the InIn termination for Zr2CoIn (0 0 1) surface. Further experimental efforts are expected to fabricate the X2CoIn thin films and investigate the structural, electronic and magnetic properties of them.

In this manuscript, the micro-mesoporous crystals with the properties of (H) ZSM-11 zeolites were successfully obtained via one-pot synthesis in the hydrothermal system by using acidified attapulgite (Si-ATP) and cetyltrimethylammonium bromide (CTAB) as a precursor source (PS) and structure-directing agent (SDA), respectively. The effect of Si-ATP/CTAB ratio on controlling the crystal morphology and hierarchical pore structure of products was systematically investigated. The synthesized materials were characterized with XPS, XRD, FTIR, NMR, SEM, TEM and N2 adsorption-desorption analysis. Results demonstrate that the products possess not only a classical zeolite framework but also an adjustable mesoporous structure accompanied with a variety of Si-ATP/CTAB ratios. Meanwhile Si-ATP/CTAB ratio has a well linear dependence with hierarchy factor (HF) in lower or higher ranges. The MFI crystal transforms gradually to the MEL-structure under the action of CTAB when Si-ATP/CTAB ratio increases to 80: 5. In addition, (H) ZSM-11 zeolite, this ratio of 80: 5, mesoporosity and adsorption capacity of MB molecules was significantly enhanced. Advanced adsorption performance is attributed to the abundance hydroxyl group and the generated mesoporosity of the zeolite surface under the participation of CTAB. The experimental data are well fitted to the Langmuir isotherm model, with a correlation coefficient of 0.9962. The excellent adsorption performance makes such hierarchically porous (H) ZSM-11 zeolites attractive for applications in the field of energy and environment.

The structural, electronic, and magnetic properties of cobalt disulfide (CoS2) doped with oxygen (O), selenium (Se), or tellurium (Te) were investigated based on the spin-polarized first-principles calculations. Both the lattice constant and volume for CoO0.25S1.75 were smaller while those for CoSe0.25S1.75 and CoTe0.25S1.75 were larger than the corresponding values for CoS2. Both CoS2 and CoO0.25S1.75 were quasi-half-metallic, and both CoSe0.25S1.75 and CoTe0.25S1.75 were quasi-metallic. For CoS2, CoSe0.25S1.75, and CoTe0.25S1.75, the valence band maximums (VBMs) were contributed by Co-3d(t2g) states near the X-point, and the conduction band minimums (CBMs) were contributed by S-3p states at the Γ-point. For CoO0.25S1.75, the VBM was contributed by Co-3d(t2g) states at the M-point, and the CBM was contributed by Co-3d(eg) states near the R-point. Both O–S and Te–S dimers were strongly polarized, and the Se–S dimer was slightly polarized. CoS2 and CoX0.25S1.75 (X = O, Se, or Te) were magnetic, and Co atoms favoured ferromagnetic interaction. Except quasi-HM CoO0.25S1.75, quasi-metallic CoX0.25S1.75, CoX0.0625S1.9375, CoX0.03125S1.96875, and perfect metallic CoX0.25S1.75*, CoX0.125S1.875, were expected more suitable for use in supercapacitor and electrocatalyst.

In this work, Cu2ZnSnS4 (CZTS) thin film was successfully prepared from four types of mixed binary sulfides nanoparticles under inert Ar atmosphere. A comparison study was conducted to explore the effect of binary sulfides with different value states on the CZTS thin films. Through X-ray diffraction (XRD), Raman and scanning electron microscopy (SEM), the pure CZTS phase can be obtained independent of the value states. However, distinguished crystallinity and morphology of CZTS were observed by using binary precursor with different value states. The grain size up to 1 µm was achieved by annealing (Cu2S+ZnS+SnS2) precursor without additional sulfur atmosphere, suggesting that value state of binary sulfides precursor play an important role in CZTS growth. This result also agrees well with our theoretical prediction. Finally, appropriate ratio of Cu/Zn/Sn was evidenced to yield an enhancement in power conversion efficiency from 0.09% (stoichiometric ratio) to 0.55% (Cu-poor, Zn-rich).

In this paper, we modify the magnetic and electronic properties of zigzag boron nitride nanoribbons (ZBNNRs) by adopting the method of edge-modification, which is achieved by passivating the edges of ZBNNRs with nonmetallic (NM) atoms H, O, S, F and P. Five different cases for XN + N-ZBNNR-B + BH, where X = H, O, S, F and P nonmetallic (NM) atoms are studied systematically. The calculated results indicate that for only X = P, the XN + N-ZBNNR-B + BH displays the half-metallic feature while the others exhibit metallic properties. The metallic feature of the XN + N-ZBNNR-B + BH (X = H, O, S, and F) systems is due to the contribution of both termination atoms and edge atoms to the total density of states at the Fermi level. The XN + N-ZBNNR-B + BH (X = H, O, S, F and P) are all magnetic materials. In addition, the half-metallic feature of the PN + N-ZBNNR-B + BH material is a new style of nano-material and a perfect candidate for spintronic applications.

Soil liquefaction poses significant threat to underground structures in seismically active areas. This paper present a detailed numerical investigation on the seismic response of underground structures in horizontally layered liquefiable grounds. A comprehensive plasticity model for large post-liquefaction shear deformation of sand is used for modelling the liquefiable soil layers. A technique of combining beam elements with quadrilateral elements is employed to simulate the response of reinforced concrete structure. Shallow buried underground structures in three typical soil profiles, including a layered liquefiable ground, a homogeneous liquefiable ground, and a homogeneous non-liquefiable ground, are analyzed under seven scaled ground motions, amounting to a total of 21 dynamic calculations. The numerical results show that the existence of a liquefiable layer passing through an underground structure can have detrimental effects on the seismic response of the structure, compared to underground structures embedded either in homogeneous liquefiable and or non-liquefiable ground, causing the structure to suffer larger deformation, bending moment, and shear force. The soil-structure interaction and inertia effects are analyzed to provide explanation for the seismic response of the underground structures.

Influence of CO molecule on structure stability and electronic properties of silver nanotube (AgNT) has been systematically investigated by using first-principles calculations based on the density-functional theory. The results indicate that the top site is the most stable for CO adsorption, which is energetically favorable than the bridge site (B1) on the AgNT's surface. The AgNT undergoes a slight structural distortion after the CO adsorption. The binding mechanism between CO and AgNT can be described by the Blyholder's model, and the donation–backdonation process between the CO and Ag states leads to the formation of bonding/antibonding pairs, 5σb/5σa and 2πb*/2πa*. The quantum conductance of the AgNT decreases 1G0 after CO adsorption, which is promising for the application of CO sensor.

Preliminary design of offshore wind turbines requires high precision simplified methods for the analysis of the system fundamental frequency. Based on the Rayleigh method and Lagrange’s Equation, this study establishes a simple formula for the analysis of system fundamental frequency in the preliminary design of an offshore wind turbine with a monopile foundation. This method takes into consideration the variation of cross-section geometry of the wind turbine tower along its length, with the inertia moment and distributed mass both changing with diameter. Also the rotational flexibility of the monopile foundation is mainly considered. The rigid pile and elastic middle long pile are calculated separately. The method is validated against both FEM analysis cases and field measurements, showing good agreement. The method is then used in a parametric study, showing that the tower length Lt, tower base diameter d0, tower wall thickness δt, pile diameter db and pile length Lb are the major factors influencing the fundamental frequency of the offshore wind turbine system. In the design of offshore wind turbine systems, these five parameters should be adjusted comprehensively. The seabed soil condition also needs to be carefully considered for soft clay and loose sand.

The electronic, magnetic and optical properties of Co doped marcasite FeS2 compounds have been investigated through the first-principles calculations. No imaginary frequency emerges in the phonon dispersion curves confirms the Fe7CoS16 and Fe6Co2S16 compounds are dynamical stable. Although the pure Fe8S16 compound is a nonmagnetic semiconductor with band gap of 1.17 eV, the Fe7CoS16 compound changes to a magnetic semiconductor with a very narrow band gap of 0.106 eV, the Fe6Co2S16 compound changes to a half-metal with half-metal band gap of 0.37 eV in spin-down channel. For all three considered configurations of the Fe6Co2S16 compound, the ferromagnetic state is preferred over antiferromagnetic state, especially for smaller separation distance of two doped Co atoms. The higher Curie temperatures than room temperature indicates the Fe6Co2S16 compound is a promising candidate for spintronics applications. In addition, the calculated optical properties shows that Fe7CoS16 and Fe6Co2S16 compounds have stronger absorption than Fe8S16 compound when the wavelength more than 500 nm, which suggests the compounds are potential candidates for solar cells.

The structural, electronic, magnetic and elastic properties for type (1) structure of half-Heusler compounds Mn2GexAs1−x (x = 0.25, 0.50, 0.75, 1.00) have been investigated within GGA and GGA + U methods. Firstly, the Mn2Ge0.5As0.5 has a tetragonal structure, while the Mn2Ge0.25As0.75, Mn2Ge0.75As0.25 and Mn2Ge present a cubic structure. Secondly, the four compounds are all half-metallic (HM) ferrimagnets and their total magnetic moments Mt satisfy with the Slater–Pauling rule Mt = 18-Zt. Thirdly, the formation energy and cohesion energy show that they are all thermodynamic stable with GGA method, while with GGA + U method the Mn2Ge0.25As0.75 is still thermodynamic stable but the rest three compounds are thermodynamic meta-stable. Finally, with GGA method both Mn2Ge0.25As0.75 and Mn2Ge0.5As0.5 are mechanical stable under pressure 0–4 GPa, while the Mn2Ge0.75As0.25 and Mn2Ge lose mechanical stable when the pressure exceed 1.3 and 0.5 GPa, respectively. But with GGA + U method the four compounds are all mechanical stable under pressure 0–4 GPa.

The structural, electronic, elastic, thermodynamic, magnetic, and optical properties of yttrium-based full-Heusler alloys of the form Y 2 CrZ (Z = Si, Ge, Sn) have been studied by first-principles calculations. The stable half-metallic ferrimagnetic characters, which are maintained in the lattice constant ranges 6.365–7.057 A ( Y 2 CrSi ), 6.496–7.163 A ( Y 2 CrGe ), and 6.515–7.385 A ( Y 2 CrSn ), ensure their potential application in spintronics and magnetoelectronics. The total magnetic moment of 2 μB per formula unit satisfies the Slater-Pauling rule M t = 18 - Z t . The formation energy E f , cohesion energy E c , spin-up band gap E g ↑ , shear modulus G , bulk modulus B , Young’s modulus E , Debye temperature Θ D , melting temperature T melt , static dielectric constant e 1 ( 0 ) , maximum imaginary part of the dielectric constant e 2 ( ω ) max , maximum reflective index R ( ω ) max , and static refractive index n ( 0 ) decrease for Y 2 CrSi , Y 2 CrGe , and Y 2 CrSn successively. Increases in both Poisson’s ratio υ and Pugh’s ratio B / G indicate the ductile character increases for Y 2 CrSi , Y 2 CrGe , and Y 2 CrSn successively. The highest global maximum value in the energy loss function L ( ω ) spectra of these three alloys indicates that Y 2 CrSn is the most suitable material to make a far-ultraviolet photodetector.

A series of centrifuge shaking table model tests are conducted on 4 × 4 pile groups in liquefiable ground in this study, achieving horizontal–vertical bidirectional shaking in centrifuge tests on piles for the first time. The dynamic distribution of forces on piles within the pile groups is analysed, showing the internal piles to be subjected to greater bending moment compared with external piles, the mechanism of which is discussed. The roles of superstructure–pile inertial interaction and soil–pile kinematic interaction in the seismic response of the piles within the pile groups are investigated through cross-correlation analysis between pile bending moment, soil displacement, and structure acceleration time histories and by comparing the test results on pile groups with and without superstructures. Soil–pile kinematic interaction is shown to have a dominant effect on the seismic response of pile groups in liquefiable ground. Comparison of the pile response in two tests with and without vertical input ground motion shows that the vertical ground motion does not significantly influence the pile bending moment in liquefiable ground, as the dynamic vertical total stress increment is mainly carried by the excess pore water pressure. The influence of previous liquefaction history during a sequence of seismic events is also analysed, suggesting that liquefaction history could in certain cases lead to an increase in liquefaction susceptibility of sand and also an increase in dynamic forces on the piles.

The structural, elastic, electronic and optical properties of FeX2 (X = S, Se, Te) with orthorhombic (space group Pnnm) structure have been investigated through the first-principles calculations. The calculated lattice constants, internal structure parameters and two kinds of Fe-X bond lengths agree reasonably with the experimental results. The corresponding single crystal elastic constants, polycrystalline elastic moduli, transverse, longitudinal, average elastic wave velocities, Debye temperature and minimum thermal conductivity decrease from FeS2 to FeTe2 while the elastic anisotropy index increases from FeS2 to FeTe2. All the three compounds show the brittle nature and covalent bonding. The orthorhombic FeX2 are non-magnetic semiconductors with indirect band gaps of 1.17eV, 0.64eV and 0.27eV, respectively. There have strong hybridizations between Fe-d orbitals and X-p orbitals. The real part and imaginary part of the dielectric function, refractive index and absorption coefficient are obtained and analyzed, the results show that the three compounds possess excellent absorption properties in ultraviolet and visible light regions. Both elastic properties and optical properties exhibit obvious anisotropy in the three compounds.

The investigations of the electronic and magnetic properties show the binary Heusler alloys ZCl3 (Z = Be, Mg, Ca, Sr) are half-metallic (HM) ferromagnets with an integer magnetic moment ( M t ) of 1 μ B /f.u.. The alloy BeCl3 is thermodynamic meta-stable, while other alloys are thermodynamic stable according to their cohesive energies and formation energies. Moreover, wide HM regions for alloys ZCl3 (Z = Be, Mg, Ca, Sr) show their HM characters are robust when the lattices are expanded or compressed under uniform and tetragonal strains. Finally, some optical properties are analyzed in detail, such as the dielectric function, the absorption coefficient, the refractive index and the extinction coefficient.

The structural, electronic, magnetic and optical properties of the yttrium-based binary Heusler alloy Y 3 Si , ternary Heusler alloy Y 2 CrSi and quaternary Heusler alloy ScYCrSi have been studied by first-principles calculations. The results show that the preferred configurations of Y 3 Si , Y 2 CrSi and ScYCrSi alloys are DO 3 - FM , Hg 2 CuTi − FM and YI − FM configurations, respectively. The Y 3 Si alloy is a conventional metal ferromagnet. While the Y 2 CrSi and ScYCrSi alloys are HM ferromagnets with spin-up band gaps of 0.682 eV and 0.862 eV as well as the HM characters are maintained in the lattice constant ranges of 6.365–7.057 A and 6.029–7.129 A, respectively, ensuring potential applications in spintronics. The total magnetic moments of the Y 2 CrSi and ScYCrSi alloys are all 2 μ B /f .u . , satisfying the Slater-Pauling rule M t = 18 - Z t . Among three alloys considered, the Y 2 CrSi alloy has the lowest static dielectric constant, static reflective index, static refractive index, global maximum energy loss function but the highest maximum imaginary part. The phonon dispersion spectra show both Y 2 CrSi and ScYCrSi alloys are dynamically stable, while the Y 3 Si alloy is dynamically unstable.

The spin-polarized first-principles are used to study the surface thermodynamic stability, electronic and magnetic properties in various (001) surfaces of Zr2CoSn Heusler alloy, and the bulk Zr2CoSn Heusler alloy are also discussed to make comparison. The conduction band minimum (CBM) of half-metallic (HM) bulk Zr2CoSn alloy is contributed by ZrA, ZrB and Co atoms, while the valence band maximum (VBM) is contributed by ZrB and Co atoms. The SnSn termination is the most stable surface with the highest spin polarizations P = 77.1% among the CoCo, ZrCo, ZrZr, ZrSn and SnSn terminations of the Zr2CoSn (001) surface. In the SnSn termination of the Zr2CoSn (001) surface, the atomic partial density of states (APDOS) of atoms in the surface, subsurface and third layers are much influenced by the surface effect and the total magnetic moment (TMM) is mainly contributed by the atomic magnetic moments of atoms in fourth to ninth layers.

The structural, electronic and magnetic properties of CoS2 under pressure have been investigated by the first-principles calculations. The lattice constant and volume decrease with increasing pressure. The CoS2 is stable and behaves a brittle characteristic under the pressures of 0–5 GPa. The CoS2 presents metallic characteristic under the pressures of 1–5 GPa although it is nearly half-metal (HM) under the pressure of 0 GPa. The lowest conduction bands for spin-up and spin-down channels shift towards higher and lower energy region, respectively, with the pressure increasing from 0 to 5 GPa. In spin-up channel the conduction band minimum (CBM) is mainly contributed by Co-3d(eg) orbitals at R point but the valence band maximum (VBM) is contributed by Co-3d(t2g) orbitals near M point. While in spin-down channel the CBM is contributed by S-3p orbitals at Γ point but the VBM is contributed by Co-3d(t2g) orbitals near X point. The CoS2 is still suitable to be used in the supercapacitor under the environmental pressures of 0–5 GPa due to the high conductivity.

We report the structural, magnetic and electronic properties of the pristine and single TM atoms X (X = Fe, Ru or Os) doped monolayer WS2 systems based on first-principle calculations. The results show that the W-S bond shows a stronger covalent bond, but the covalency is obviously weakened after the substitution of W atom with single X atoms, especially for Ru (4d75s1) with the easily lost electronic configuration. The smaller total energies of the doped systems reveal that the spin-polarized states are energetically favorable than the non-spin-polarized states, and the smallest total energy of −373.918 eV shows the spin-polarized state of the Os doped monolayer WS2 system is most stable among three doped systems. In addition, although the pristine monolayer WS2 system is a nonmagnetic-semiconductor with a direct band gap of 1.813 eV, single TM atoms Fe and Ru doped monolayer WS2 systems transfer to magnetic-HM with the total moments M tot of 1.993 and 1.962 μ B , while single TM atom Os doped monolayer WS2 systems changes to magnetic-metal with the total moments M tot of 1.569 μ B . Moreover, the impurity states with a positive spin splitting energies of 0.543, 0.276 and 0.1999 eV near the Fermi level E F are mainly contributed by X - d xy and X - d x 2 - y 2 states hybridized with its nearest-neighbor atom W - d z 2 states for Fe, Ru and Os doped monolayer WS2 system, respectively. Finally, we hope that the present study on monolayer WS2 will provide a useful theoretical guideline for exploring low-dimensional spintronic materials in future experiments.

The structural, electronic, and magnetic properties of (ZnO) 12 clusters doped with Cr atoms have been investigated by using spin-polarized first-principles calculations. The exohedral a3 isomer is favorable than endohedral a2 isomer. The isomer a1 and a5 respectively have the narrowest and biggest gap between highest unoccupied molecular orbital and the lowest unoccupied molecular orbital (HOMO-LUMO) of 0.473 and 1.291 eV among these five monodoped isomers. The magnetic moment may be related to the local environment around the Cr atom that the a2 isomer whose total magnetic moment is 6 μ B while the other monodoped isomers which all isomers have nearly total magnetic moments 4 μ B . For Cr-doped (ZnO)12 on a1 or a3 isomer, the DOS of spin-up channel cross the Fermi level EF showing a finite magnitude near the Fermi level which might be useful for half metallic character. For the bidoped cases, the exohedral isomers are found to be most favorable. Including all bipoed isomers of substitutional, exohedral and endohedral bidoped clusters, the total magnetic moment of the ferromagnetic (antiferromagnetic) state is 8 (0) μ B and the HOMO-LUMO gap of antiferromagnetic state is slightly larger than that of ferromagnetic state. The magnetic coupling between the Cr atoms in bidoped configurations is mainly governed by the competition between direct Cr and Cr atoms antiferromagnetic interaction and the ferromagnetic interaction between two Cr atoms via O atom due to strong p-d hybridization. Most importantly, we show that the exohedral bidoped (ZnO)12 clusters favor the ferromagnetic state, which may have the future applications in spin-dependent magneto-optical and magneto-electrical devices.

In this study, the high-energy ball-milled nanodiamonds (MNDs) are carefully treated with low-temperature annealing and mixed acids to obtain carboxylated MNDs (cMNDs). This process not only removes impurities but also grafts oxygen containing functional groups onto MNDs surfaces. Then poly (vinyl alcohol) (PVA)/cMND nanocomposites are prepared by a facile aqueous solution casting method. Compared with PVA/MND, an improved dispersion of nanoparticles in the matrix and higher nanoparticles content can be achieved by PVA/cMND. It is found that glass transition temperature (Tg) and loss factor peak temperature (Ttanδ) of PVA/cMND nanocomposites are both shifted to higher values than pure PVA. Thermal decomposition of PVA is obviously suppressed by cMNDs. The onset and maximum decomposition temperatures increases by over 17 °C and 24 °C, respectively. The thermal conductivity increases by 57.5%. Furthermore, tensile strength and Young’s modulus of PVA are improved by 62.3% and 166.7% with the addition of cMNDs.

The density functional theory calculations using general gradient approximation (GGA) applying Perdew–Burke–Ernzerhof (PBE) as correlation functional have been systematically performed to research the formation energy, the electronic structures, band structures, total and partial DOS, and optical properties of Nd doping ZnO with the content from 6.25% to 12.5%. The formation energies are negative for both models, which show that two structures are energetically stable. Nd doping ZnO crystal is found to be a direct band gap semiconductor and Fermi level shifts upward into conduction band, which show the properties of n-type semiconductor. Band structures are more compact after Nd doping ZnO, implying that Nd doping induces the strong interaction between different atoms. Nd doping ZnO crystal presents occupied states at near Fermi level, which mainly comes from the Nd 4f orbital. The calculated optical properties imply that Nd doping causes a red-shift of absorption peaks, and enhances the absorption of the visible light.

The geometrical evolution, local relative stability, magnetism and charge transfer characteristics of Pd n H m ( n = 1–10, m = 1,2) have been systematically calculated by using density functional theory. The studied results show that the most stable geometries of Pd n H and Pd n H 2 ( n = 1–10) can be got by doping one or two H atoms on the sides of Pd n clusters except Pd 6 H and Pd 6 H 2 . It is found that doping one or two H atoms on Pd n clusters cannot change the basic framework of Pd n . The analysis of stability shows that Pd 2 H, Pd 4 H, Pd 7 H, Pd 2 H 2 , Pd 4 H 2 and Pd 7 H 2 clusters have higher local relative stability than neighboring clusters. The analysis of magnetic properties demonstrates that absorption of hydrogen atoms decreases the average atomic magnetic moments compared with pure Pd n clusters. More charges transfer from H atoms to Pd atoms for Pd 6 H and Pd 6 H 2 clusters, demonstrating the adsorption of hydrogen atoms change from side adsorption to surface adsorption.

The electronic, optical and magnetic properties of Ce doped ZnO crystal have been studied by using first principles method. The research of formation energies show that Ce doped ZnO is energetically stable, and the formation energies reduce from 6.25% to 12.5% for Ce molar percentage. The energy band is still direct band gap after Ce doped, and band gap increases with the increase of Ce Ce distance. The Fermi level moves upward into conduction band and the DOS moves to lower energy with the increase of Ce concentration, which showing the properties of n-type semiconductor. The calculated optical properties imply that Ce doped causes a red-shift of absorption peaks, and enhances the absorption of the visible light. The transition from ferromagnetic to antiferromagnetic has been found in Ce doped ZnO.

Analysis of the seismic response of high CFRDs under non-uniform ground motion input is conducted using a novel non-uniform input motion calculation method combined with nonlinear FEM. The non-uniform input motion calculation method and its basic assumption are validated. The response of CFRDs under uniform and non-uniform input is compared to discuss the necessity of conducting seismic analysis of high CFRDs under realistic non-uniform ground motion input. When the acceleration at the surface of the free field for dynamic simulations with uniform and non-uniform input is kept consistent, the seismic response of CFRDs under non-uniform input is in general significantly smaller, while the dynamic tensile stress around the edges of the concrete face slab is greater. The simulation results suggest that non-uniformity of the ground motion input has important effects on the seismic response of high CFRDs and should be considered in the seismic design of CFRDs. The influence of the incident angle of seismic waves is also investigated, with results indicating that the influence is waveform dependent, while being frequency independent.

We have performed a comprehensive calculation about the structures, energy band structures, total and partial density of states of Y doping ZnO with different concentration using the density-functional theory (DFT). The Y doping structures still maintain wurtzite configuration with the increasing of Y content. The research of formation energy shows that Y doping ZnO crystal is energetically stable, and the formation energies reduce with the increasing of Y molar content from 3.125% to 12.5%. The Y doping system exhibits direct band gap like pure ZnO. The Fermi level of doping ZnO crystal shifts upward into conduction, showing the properties of n-type semiconductor and the band gaps of Y doping are larger than that of pure ZnO. There exists a strong localized state at near 5 eV in conduction band, which mainly comes from Y-4d states. The DOS of concentration 12.5% appears a new strong peak at near −24 eV, which mainly originates from the Y-4p states.

We study the structural, electronic and magnetic properties of 3d transition metal (TM) atoms (Cr, Mn, Fe, Co, Ni and Cu) adsorbed GaN monolayer (GaN-ML) using first-principles calculations. The results show that, for 6 different TM adatoms, the most stable adsorption sites are the same. The adsorption of TM atoms results in significant lattice distortions. A covalent chemical bonding character between TM adatom and GaN-ML is found in TM adsorbed systems. Except for Ni adsorbed system, all TM adsorbed systems show spin polarization implying that the adsorption of TM induces magnetization. The magnetic moments of the adsorbed systems are concentrated on the TM adatoms and the nearest-neighbor N atoms of the adsorption site contributed slightly. Our analysis shows that the GaN-ML properties can be effectively modulated by TM adsorption, and exhibit various electronic and magnetic properties, such as magnetic metals (Fe adsorption), half-metal (Co adsorption), and spin gapless semiconductor (Cu adsorption). These present properties of TM adsorbed GaN-ML may be of value in electronics and spintronics applications.

The structural, electronic, magnetic and optical properties of the Zn1−xMoxTe (x = 0.00, 0.25, 0.50, 0.75, 1.00) have been investigated by the spin-polarized first-principles calculations. The Zn0.50Mo0.50Te has tetragonal structure while the Zn1−xMoxTe (x = 0.00, 0.25, 0.75, 1.00) crystallize in cubic structures. For Zn1−xMoxTe (x = 0.25, 0.50, 0.75, 1.00) alloys, the lattice constant and the volume are found larger than those of pure ZnTe alloy. The Zn1−xMoxTe (x = 0.25, 0.50, 0.75, 1.00) is magnetic and the Mo element is found dominant in the bands crossing the Fermi level in the spin-up channel. The Zn0.75Mo0.25Te and MoTe have half-metallic (HM) behavior. In spin-down channel of the Zn0.75Mo0.25Te, the Zn atom mainly contributed to the conduction band minimum (CBM), while the valence band maximum (VBM) appears mainly due to contribution of Te element. A positive spin splitting and crystal field splitting of d-states of Mo atom has been observed for Zn0.75Mo0.25Te alloy. The maximum values of the absorption coefficients α M A X ( ω ) of the Zn0.50Mo0.50Te alloy along a or b axes are smaller than the absorption coefficient along c axis. The first absorption peak appearing in the energy range of 0.000–1.000 eV for Zn1−xMoxTe (x = 0.25, 0.50, 0.75 or 1.00) alloys is the new peak which is not observed in ZnTe.

In this paper, the geometrical, electronic, and magnetic properties of nonmetal (N, F) atom doping g-ZnO monolayer supercell forming 6.25, 12.5, and 25% concentrations have been investigated comprehensively using the first-principles method. The structural optimization implies that N or F atom doping g-ZnO monolayer causes the structural distortion around the doping atoms. Doping g-ZnO monolayer with one N atom is FM semiconductor, and the total magnetic moment is 0.651 μB. The N–N-pair or two N–N-pair doping g-ZnO is AFM states. The total magnetic moments mainly originate from the spin polarization of the doping atom N, and the rest comes from the nearest Zn and O atoms. Doping g-ZnO with F atoms with the concentrations of 6.25, 12.5, and 25% all are nonmagnetic semiconductor. The F-doping can adjust energy band gap, which increases with the increase of F concentration.

Doping protocols have been widely investigated due to their effectiveness in tuning the energy band gaps of photocatalysts for improved photocatalytic activity. Here, we demonstrated the efficient and facile hydrogen peroxide-assisted hydrothermal reforming of melamine to synthesize a new oxygen (O)-doped precursor that was then transferred to O-doped g-C3N4 nanosheets, with an increased conductive band edge compared to bulk g-C3N4, via direct thermal polymerization. Owing to synergistic interaction between the 2D ultrathin nanosheet structure with large surface area and the enhanced conductive band edge caused by appropriate oxygen doping, the as-synthesized O-doped g-C3N4 nanosheets showed highly enhanced photocatalytic hydrogen evolution activity, about 10.7 times higher than pristine C3N4 under visible light irradiation, achieving an apparent quantum yield of 13.04% at 420 nm. Significantly, this precursor pre-doping strategy might provide a promising pathway for preparing heteroatom-doped g-C3N4.

PbPdO2, PbPd0.9V0.1O2 and PbPd0.9Gd0.1O2 thin films with body-centered orthorhombic structure were prepared by PLD technique, respectively. Their structures, magnetic and electrical properties were measured by XRD, SEM, AFM, EDS, XPS and VSM, respectively. The experimental results indicate that the three samples all have the preferred orientation of (002), and room temperature ferromagnetism. From EDS and XPS results, we can deduce that there exist Pb vacancies in the three samples. Meanwhile, the valence states for Pb, Pd, O, Gd and V ions were found to be 2+, 2+, 2−, 3+ and mixed 4+ and 5+, respectively. It was also found that the magnetic moments of PbPdO2 and PbPd0.9Gd0.1O2 are least and largest, respectively. Moreover, the electrical characteristics analysis indicates that the electrical resistivity is enhanced by V ion substitution, but reduced by Gd ion substitution. In addition, the significant insulator–metal transition temperatures of PbPdO2, PbPd0.9V0.1O2 and PbPd0.9Gd0.1O2 were found to be about 385 K, 390 K and 430 K, respectively. Finally, according to the experimental facts of Pb vacancies in the three samples, the first-principles calculated models containing Pb vacancies were established. The calculated results explain well the magnetic origin of PbPdO2, and V and Gd doping roles on its electrical and magnetic properties.

Increasing number of offshore wind farm projects with wind turbines supported by suction bucket foundation in mildly sloping sandy seabed have being planned in earthquake-prone areas. Hence, it is crucial to evaluate the seismic performance of suction bucket foundations for offshore wind turbines in such liquefiable ground, especially considering the interaction between the bucket and both outside and inside bucket soil. Based on a pair of centrifuge shaking table tests, the seismic response of the bucket foundations and turbines in liquefiable ground is evaluated in this study. The dynamic response of soil, foundation, and turbine are presented. The test results indicate that the horizontal displacement of mildly sloping liquefiable seabed during earthquakes can results in excessive displacement and rotation of the bucket foundation. The influence of inside-bucket soil on foundation and turbine response, and especially on the kinematic and inertial interactions of the system are analyzed in detail. The analysis results indicate that inside-bucket soil plays an important role in stabilizing the foundation-turbine system during earthquakes, restricting the displacement and rotation of the foundation and the acceleration of the turbine.

Recently, van der Waals (vdW) heterostructures have attracted extensive research interest due to their extraordinary properties and potential applications in photovoltaic and photocatalytic devices. Here, we propose As/CdO vdW heterostructure with compelling optical and photocatalytic properties which has been studied by means of first-principles calculations. The stability of the heterostructure is verified by calculating the binding energy and ab-initio molecular dynamics simulations. We demonstrate that the As/CdO vdW heterostructure possesses a direct band gap of about 1.96 eV with type-II (staggered) band alignment, which can effectively reduce the recombination of photogenerated electron-hole pairs. Compared with two isolated parts, As/CdO vdW heterostructure shows suitable band edge positions and high absorption efficiency in the visible and ultraviolet light regions, making it a good candidate for optical devices and photocatalytic water splitting. The calculated higher carrier mobility of holes and electrons along the armchair direction are 932.510 cm 2 V−1 s−1 and 90.808 cm2 V−1 s−1, respectively. Biaxial strain can modulate the electronic structure and optical characteristics of As/CdO vdW heterostructure. In particular, compressive strain shows robust type-II band alignment and improve the optical performance of As/CdO vdW heterostructure in the visible light region. Our results are beneficial for designing optoelectronic and photocatalytic devices.

The electronic structures, magnetic properties , magnetic coupling and photocatalytic properties of Si-doping (4 × 4) graphene-like ZnO (g-ZnO) monolayer without or with defects including V O and VZn have been calculated using the first-principles method. Si doping ZnO can increase the electronic state near Fermi level and introduce impurity state into the band gap due to P-type doping. The impurity state introduced by Si doping makes the system transition from NM to FM. The analysis of Ef indicates that Si doping makes ZnO thin films easy to form V Zn. VO leads to two weakly bound Zn-4s electrons, VZn leads to two weakly bound O-2p electrons, both of them can form impurity level near Fermi level, thus affecting the magnetic properties of g-ZnO monolayer. The analysis of magnetic coupling characteristics shows that the doping system undergoes a transition from NM to FM. Because the impurity state introduced by Si doping is beneficial to the excitation of electrons, Si doping can also reduce the gap between Fermi level and conduction band . The calculation result of optical properties shows that Si doping has strong absorption to visible light.

We use the first-principle methods to systematically study the structural, electronic, magnetic and optical characteristics of the perfect and Co-X (X = B, C, N, O or F) codoped single-layer WS2. The results show that firstly, all Co-X (X = B, C, N, O or F) codoped single-layer WS2 are easier to form in S-rich environment than in W-rich environment. Second, although the perfect single-layer WS2 is non-magnetic semiconductor (NM-SC), the Co-X (X = B, C, N or F) codoped single-layer WS2 become to magnetic semiconductor (M − SC) with magnetic moments 2, 3, 2 or 2 μ B , while the Co–O codoped single-layer WS2 transforms to magnetic half metal (M-HM) with magnetic moment 1 μ B . Thirdly, comparing with the perfect single-layer WS2, the Co-X (X = B, C, N, O or F) codoped single-layer WS2 show not only the red-shifted absorption edges but also enhanced absorption rate in infrared and visible light region, implying the Co-X (X = B, C, N, O or F) codoped single-layer WS2 have great application prospects in infrared and visible light detection.

Two-dimensional magnetic materials are high desirable for realizing advanced optoelectronic and spintronic devices. In this paper, we report systematic studies the effects of strain on the electronic structure, magnetic states and optical properties of Mn-doped SnS 2 monolayer (ML) by means of first-principles calculations. Ab-initio molecular dynamics simulations and formation energy reveal that the Mn-doped SnS2 ML is stable at 500 K and can be fabricated under the S-rich condition. The substitution of a Mn for a Sn atom induces 3 μB magnetic moment in nonmagnetic SnS 2 ML, which is consistent with the Hund's rule and Aufbau principle. Based on classical Heisenberg model and mean-field approximation the Curie temperature is calculated to be 476.13 K. Due to symmetry reserved crystal structure, the net magnetic moment of Mn-doped SnS 2 ML is robust even if considerable strains (−10 to 10%) are applied. The blue-shift and red-shift of the absorption peaks are observed in the optical spectrum by biaxial compressive and tensile strains . The biaxial strain effectively improves the optical properties of Mn-doped SnS 2 ML, particularly in the visible light region. This study provide useful guidance for practical application in magnetic and optoelectronic devices .

Two-dimensional black phosphorene (BP) has attracted much interest for application in electronic devices. Contacts between BP and metal electrodes are critical components of BP-based devices and can dramatically affect device performances. In this paper, we adopted first-principles calculations to explore binding energies, electronic structures, and potential distribution for interface systems of Al-, Au-, Cu-, Ni-, and Ti-monolayer BP in surface contact and edge contact (EC) types. Moreover, we also used density functional theoretical coupled with the nonequilibrium Green’s function method to investigate contact resistances and Schottky barrier heights (SBHs) for transport systems of monolayer BP with Al, Au, Cu, Ni, and Ti electrodes. Our calculated results indicate that the contact type between BP and metals may greatly affect electrical properties of BP–metal contacts. Changing contact type between metal electrodes and BP channel can change the type of Schottky barrier of metal–BP contacts. The contact barrier of metal–BP depends on the metal material. Selecting an appropriate contact type and metal can effectively regulate the contact barrier of metal–BP. Specifically exciting, our estimated lateral SBHs for the Ni–BP system in EC-type agree well with the experimental results. We have provided a new strategy on choosing an appropriate contact type to achieve low contact resistance for the metal–BP interface.

Earthquakes are considered as the major trigger of submarine landslides. This study analyzes the large-scale seismic seafloor stability in the South China Sea (SCS), taking into consideration the earthquake probability and spatial distribution of seismicity and seafloor soil properties. For this cause, the geographical, seismic, and seafloor soil characteristics are first determined. The digital elevation model (DEM) of the study area is established using the geographic information system (GIS). Large-scale Peak Ground Acceleration (PGA) maps under different exceedance probabilities (EPs) are derived using the Chinese Probability Seismic Hazard Analysis (CPSHA) method. Three-dimension continuous models for seafloor soil properties are obtained using a proposed best-fit distribution-based Kriging method. With this information, the large-scale seafloor stability under different EPs is evaluated with an infinite slope model in the study area of the SCS. The proposed large-scale seismic seafloor stability is validated against recorded earthquake-induced submarine landslides. The analysis shows that the seafloor stability is found to be highly nonuniform, and the study area can be divided into three main parts based on their distinct seafloor stabilities. This study sheds new light on the large-scale seafloor stability, and can assist the development of ocean engineering projects in the SCS.

The ferromagnetic properties and origin of P doping graphene-ZnO (g-ZnO) monolayer without or with defects including O vacancy (VO) and Zn vacancy (VZn) are discussed in detail using the first principles method in this paper. In order to describe the electronic structure correctly, the GGA + U (PBE functional in GGA) method is adopted. The most stable structures of P doping g-ZnO monolayer without or with defects including VO and VZn are obtained. When O atoms in g-ZnO monolayer is replaced by P, the impurity level caused by P is near Fermi level and P-3p orbital is spin polarized, and the system is ferromagnetic. VZn produce weakly bound O-2p electrons, which spin in the same direction and leads to the ferromagnetism of g-ZnO system. Both of the mechanism can be obtained at room temperature. Meanwhile Curie temperature (Tc) of Zn16O15P1 and Zn16O14P2 is higher than room temperature. Therefore, P doping ZnO monolayer is a potential diluted magnetic semiconductor.