Xiaoying Zhuang | Tongji University (original) (raw)

Papers by Xiaoying Zhuang

Batteries

Recently, benzotrithiophene graphdiyne (BTT-GDY), a novel two-dimensional (2D) carbon-based mater... more Recently, benzotrithiophene graphdiyne (BTT-GDY), a novel two-dimensional (2D) carbon-based material, was grown via a bottom-up synthesis strategy. Using the BTT-GDY lattice and by replacing the S atoms with N, NH and O, we designed three novel GDY lattices, which we named BTHP-, BTP- and BTF-GDY, respectively. Next, we explored structural, electronic, mechanical, optical, photocatalytic and Li-ion storage properties, as well as carrier mobilities, of novel GDY monolayers. Phonon dispersion relations, mechanical and failure behavior were explored using the machine learning interatomic potentials (MLIPs). The obtained HSE06 results reveal that BTX-GDYs (X = P, F, T) are direct gap semiconductors with band gaps in the range of 2.49–2.65 eV, whereas the BTHP-GDY shows a narrow indirect band gap of 0.06 eV. With appropriate band offsets, good carrier mobilities and a strong capability for the absorption of visible and ultraviolet range of light, BTF- and BTT-GDYs were predicted to be pr...

Computational methods in engineering & the sciences, 2023

We present a general finite deformation higher-order gradient elasticity theory. The governing eq... more We present a general finite deformation higher-order gradient elasticity theory. The governing equations of the higher-order gradient solid along with boundary conditions of various orders are derived from a variational principle using integration by parts on the surface. The objectivity of the energy functional is achieved by carefully selecting the invariants under rigid-body transformation. The third-order gradient solid theory includes more than 10.000 material parameters. However, under certain simplifications, the material parameters can be greatly reduced; down to 3. With this simplified formulation, we develop a nonlocal operator method and apply it to several numerical examples. The numerical analysis shows that the high gradient solid theory exhibits a stiffer response compared to a 'conventional' hyperelastic solid. The numerical tests also demonstrate the capability of the nonlocal operator method in solving higher-order physical problems.

Computational methods in engineering & the sciences, 2023

In this paper we develop a new Peridynamic approach that naturally includes varying horizon sizes... more In this paper we develop a new Peridynamic approach that naturally includes varying horizon sizes and completely solves the "ghost force" issue. Therefore, the concept of dual-horizon is introduced to consider the unbalanced interactions between the particles with different horizon sizes. The present formulation is proved to fulfill both the balances of linear momentum and angular momentum. Neither the "partial stress tensor" nor the "'slice" technique are needed to ameliorate the ghost force issue in [1]. The consistency of reaction forces is naturally fulfilled by a unified simple formulation. The method can be easily implemented to any existing peridynamics code with minimal changes. A simple adaptive refinement procedure is proposed minimizing the computational cost. The method is applied here to the three Peridynamic formulations, namely bond based, ordinary state based and nonordinary state based Peridynamics. Both two-and three-dimensional examples including the Kalthof-Winkler experiment and plate with branching cracks are tested to demonstrate the capability of the method in solving wave propagation, fracture and adaptive analysis .

Coatings

In the latest ground-breaking experimental advancement (Nature (2022), 606, 507), zero-dimensiona... more In the latest ground-breaking experimental advancement (Nature (2022), 606, 507), zero-dimensional fullerenes (C60) have been covalently bonded to form single-layer two-dimensional (2D) fullerene network, namely quasi-hexagonal-phase fullerene (qHPC60). Motivated by the aforementioned accomplishment, in this communication, for the first time, we explore the phononic and mechanical properties of the qHPC60 monolayer, employing state-of-the-art machine-learning interatomic potentials. By employing an efficient passive-training methodology, the thermal and mechanical properties were examined with an ab-initio level of accuracy using the classical molecular dynamics simulations. Predicted phonon dispersion confirmed the desirable dynamical stability of the qHPC60 monolayer. Room temperature lattice thermal conductivity is predicted to be ultralow and around 2.9 (5.7) W/m·K along the x(y) directions, which are by three orders of magnitude lower than that of the graphene. Close to the gro...

Advanced Energy Materials

Accurate examination of electricity generation stemming from higher‐order deformation (flexoelect... more Accurate examination of electricity generation stemming from higher‐order deformation (flexoelectricity) in 2D layered materials is a highly challenging task to be investigated with either conventional computational or experimental tools. To address this challenge herein an innovative and computationally efficient approach on the basis of density functional theory (DFT) and machine‐learning interatomic potentials (MLIPs) with incorporated long‐range interactions to accurately investigate the flexoelectric energy conversion in 2D van der Waals (vdW) bilayers is proposed. In this approach, short‐range interactions are accurately defined using the moment tensor potentials trained over computationally inexpensive DFT‐based datasets. The long‐range electrostatic (charge and dipole) and vdW interaction parameters are calibrated from DFT simulations. Elaborated comparison of mechanical and piezoelectric properties extracted from the herein proposed approach with available data confirms the...

FlatChem, 2021

In a latest experimental advance, graphene-like and insulating BeO monolayer was successfully gro... more In a latest experimental advance, graphene-like and insulating BeO monolayer was successfully grown over silver surface by molecular beam epitaxy (ACS Nano 15(2021), 2497). Inspired by this accomplishment, in this work we conduct first-principles based simulations to explore the electronic, mechanical properties and thermal conductivity of graphene-like BeO, MgO and CaO monolayers. The considered nanosheets are found to show desirable thermal and dynamical stability. BeO monolayer is found to show remarkably high elastic modulus and tensile strength of 408 and 53.3 GPa, respectively. The electronic band gap of BeO, MgO and CaO monolayers are predicted to be 6.72, 4.79, and 3.80 eV, respectively, using the HSE06 functional. On the basis of iterative solutions of the Boltzmann transport equation, the room temperature lattice thermal conductivity of BeO, MgO and CaO monolayers are predicted to be 385, 64 and 15 W/mK, respectively. Our results reveal substantial decline in the electronic band gap, mechanical strength and thermal conductivity by increasing the weight of metal atoms. This work highlights outstandingly high thermal conductivity, carrier mobility and mechanical strength of insulating BeO nanosheets and suggest them as promising candidates to design strong and insulating components with high thermal conductivities.

Materials Today Nano, 2021

Beryllium polynitrides, BeN4 is a novel layered material, which has been most recently fabricated... more Beryllium polynitrides, BeN4 is a novel layered material, which has been most recently fabricated under high pressure (Phys. Rev. Lett. 126(2021), 175501). As a new class of 2D materials, in this work we conduct first-principles calculations to examine the stability and explore the electronic nature of MN4 (M= Be, Mg, Ir, Rh, Ni, Cu, Au, Pd, Pt) monolayers. Acquired results confirm the dynamical and thermal stability of BeN4, MgN4, IrN4, PtN4 and RhN4 monolayers. Interestingly, BeN4 and MgN4 monolayers are found to show anisotropic Dirac cones in their electronic structure. While PtN4 monolayer is predicted to be a narrow band-gap semiconductor, IrN4 and RhN4 monolayers are found to be metallic systems. We also elaborately explore the effects of number of atomic layers on the electronic features of BeN4 nanosheets, which reveal highly appealing physics. Our results highlight that BeN4 nanosheet yield ultrahigh elastic modulus and mechanical strength, outperforming all other carbon-free 2D materials. Notably, RhN4 nanosheet is predicted to yield high capacities of 562, 450 and 900 mAh/g, for Li, Na and Ca ions storages, respectively. This study provides a comprehensive understanding on the intrinsic properties of MN4 nanosheets and highlight their outstanding physics.

Carbon, 2021

Examination of thermal expansion of two-dimensional (2D) nanomaterials is a challenging theoretic... more Examination of thermal expansion of two-dimensional (2D) nanomaterials is a challenging theoretical task with either ab-initio or classical molecular dynamics simulations. In this regard, while ab-initio molecular dynamics (AIMD) simulations offer extremely accurate predictions, but they are excessively demanding from computational point of view. On the other side, classical molecular dynamics simulations can be conducted with affordable computational costs, but without predictive accuracy needed to study novel materials and compositions. Herein, we explore the thermal expansion of several carbon-based nanosheets on the basis of machine-learning interatomic potentials (MLIPs). We show that passively trained MLIPs over inexpensive AIMD trajectories enable the examination of thermal expansion of complex nanomembranes over wide range of temperatures. Passively fitted MLIPs could also with outstanding accuracy reproduce the phonon dispersion relations predicted by density functional theory calculations. Our results highlight that the devised methodology on the basis of passively trained MLIPs is computationally efficient and versatile to accurately examine the thermal expansion of complex and novel materials and compositions using the molecular dynamics simulations.

Carbon, 2020

Carbon nitride two-dimensional (2D) materials are among the most attractive class of nanomaterial... more Carbon nitride two-dimensional (2D) materials are among the most attractive class of nanomaterials, with wide range of application prospects. As a continuous progress, most recently, two novel carbon nitride 2D lattices of C 3 N 5 and C 3 N 4 have been successfully experimentally realized. Motivated by these latest accomplishments and also by taking into account the well-known C 3 N 4 triazine-based graphitic carbon nitride structures, we predicted two novel C 3 N 6 and C 3 N 4 counterparts. We then conducted extensive density functional theory simulations to explore the thermal stability, mechanical, electronic and optical properties of these novel nanoporous carbon-nitride nanosheets. According to our results all studied nanosheets were found to exhibit desirable thermal stability and mechanical properties. Non-equilibrium molecular dynamics simulations on the basis of machine learning interatomic potentials predict ultralow thermal conductivities for these novel nanosheets. Electronic structure analyses confirm direct band gap semiconducting electronic character and optical calculations reveal the ability of these novel 2D systems to adsorb visible range of light. Extensive first-principles based results by this study provide a comprehensive vision on the stability, mechanical, electronic and optical responses of C 3 N 4 , C 3 N 5 and C 3 N 6 as novel 2D semiconductors and suggest them as promising candidates for the design of advanced nanoelectronics and energy storage/conversion systems.

Applied Physics A, 2021

In this work, extensive reactive molecular dynamics simulations are conducted to analyze the nano... more In this work, extensive reactive molecular dynamics simulations are conducted to analyze the nanopore creation by nanoparticles impact over single-layer molybdenum disulfide (MoS2) with 1T and 2H phases. We also compare the results with graphene monolayer. In our simulations, nanosheets are exposed to a spherical rigid carbon projectile with high initial velocities ranging from 2 to 23 km/s. Results for three different structures are compared to examine the most critical factors in the perforation and resistance force during the impact. To analyze the perforation and impact resistance, kinetic energy and displacement time history of the projectile as well as perforation resistance force of the projectile are investigated. Interestingly, although the elasticity module and tensile strength of the graphene are by almost five times higher than those of MoS2, the results demonstrate that 1T and 2H-MoS2 phases are more resistive to the impact loading and perforation than graphene. For the...

Materials Horizons, 2020

We highlight that machine-learning interatomic potentials trained over short AIMD trajectories en... more We highlight that machine-learning interatomic potentials trained over short AIMD trajectories enable first-principles multiscale modeling, bridging DFT level accuracy to the continuum level and empowering the study of complex/novel nanostructures.

Applied Materials Today, 2020

Phononic properties are commonly studied by calculating force constants using the density functio... more Phononic properties are commonly studied by calculating force constants using the density functional theory (DFT) simulations. Although DFT simulations offer accurate estimations of phonon dispersion relations or thermal properties, but for low-symmetry and nanoporous structures the computational cost quickly becomes very demanding. Moreover, the computational setups may yield nonphysical imaginary frequencies in the phonon dispersion curves, impeding the assessment of phononic properties and the dynamical stability of the considered system. Here, we compute phonon dispersion relations and examine the dynamical stability of a large ensemble of novel materials and compositions. We propose a fast and convenient alternative to DFT simulations which derived from machine-learning interatomic potentials passively trained over computationally efficient ab-initio molecular dynamics trajectories. Our results for diverse two-dimensional (2D) nanomaterials confirm that the proposed computational strategy can reproduce fundamental thermal properties in close agreement with those obtained via the DFT approach. The presented method offers a stable, efficient, and convenient solution for the examination of dynamical stability and exploring the phononic properties of low-symmetry and porous 2D materials.

Journal of Materials Chemistry C, 2020

Mechanical response, dynamical/thermal stability, electronic/optical properties and photocatalyti... more Mechanical response, dynamical/thermal stability, electronic/optical properties and photocatalytic features of monoclinic As2X3 (X = S, Se and Te) nanosheets are explored via DFT simulations. As2Te3 lattice predicted by this study is found to exhibit superior superstretchability, outperforming other known 2D materials.

Coatings, 2019

Group IV–V-type layered materials, such as SiP, SiAs, GeP and GeAs, are among the most attractive... more Group IV–V-type layered materials, such as SiP, SiAs, GeP and GeAs, are among the most attractive two-dimensional (2D) materials that exhibit anisotropic mechanical, optical and transport properties. In this short communication, we conducted density functional theory simulations to explore the prospect of SiP, SiAs, GeP and GeAs nanosheets for the water-splitting application. The semiconducting gaps of stress-free SiP, SiAs, GeP and GeAs monolayers were estimated to be 2.59, 2.34, 2.30 and 2.07 eV, respectively, which are within the desirable ranges for the water splitting. Moreover, all the considered nanomaterials were found to yield optical absorption in the visible spectrum, which is a critical feature for the employment in the solar water splitting systems. Our results furthermore confirm that the valence and conduction band edge positions in SiP, SiAs, GeP and GeAs monolayers also satisfy the requirements for the water splitting. Our results highlight the promising photocataly...

Underground Space, 2018

In this study, we present an adaptive phase field method (APFM) for modeling quasi-static crack p... more In this study, we present an adaptive phase field method (APFM) for modeling quasi-static crack propagation in rocks. Crack initiation due to positive strains is considered, and a numerical simulation is implemented using a commercial software, COMSOL Multiphysics. Two benchmark tests are first examined, namely, a single-edge-notched square plate subjected to respective tension and shear loadings. The crack propagation in Brazil splitting tests, 2D notched semi-circular bend (NSCB) tests, and 3D NSCB tests are subsequently simulated and analyzed. All the numerical examples indicate that the propagation of the cracks is autonomous and external fracture criteria are not required for phase field modeling. Furthermore, the adaptive remeshing scheme reduces unnecessary global mesh refinement and exhibits good adaptability for fracture modeling. The simulations are in good agreement with the experimental observations, and thereby indicate the feasibility and practicability of the APFM in rocks (even in 3D cases).

Materials (Basel, Switzerland), Jan 31, 2018

An amorphous polyethylene/silica (PE/S) interface exists in many materials. However, the research... more An amorphous polyethylene/silica (PE/S) interface exists in many materials. However, the research of the interfacial properties at microscale is lacking. Shear failure and adhesion properties of an amorphous PE/S interface are studied by molecular dynamics. The effects of PE chain length, the number of chains, and coupling agents on the shear behavior and interfacial adhesion are investigated. It is found that the modified silica (mS) surface induces an increase in the adhesion strength compared to unmodified S. The damage process and failure mode of the PE/S and PE/mS interface are analyzed at microscale. The contribution of bond length, bond angle, torsional potentials, and nonbonded energy is estimated as a function of the shear deformation to clarify the deformation mechanisms. The energy partitioning results indicate that the elastic, yield, and postyielding regions are mostly controlled by the nonbonded interactions. The dihedral motions of the chains also have an influence. F...

International Journal of Fracture, 2016

A multiscale computational homogenization method for the modeling of hydro-mechanical coupling pr... more A multiscale computational homogenization method for the modeling of hydro-mechanical coupling problem for quasi-brittle materials is developed. The present method is based on an asymptotic expansion homogenization combined with the semiconcurrent finite element modelling approach. Modified periodic boundary conditions and a molecular dynamics (MD) based inclusion or filler generation procedure are devised for the hydro-mechanical coupling problem. A modified elastic damage constitutive model and a damage induced permeability law have been developed for the hydraulic fracturing. The statistical convergence of the microscale representative volume element (RVE) model regarding the RVE characteristic size is studied. It was found that the RVE characteristic size is determined by both the mechanical and hydraulic properties of the RVE simultaneously. The present method is validated by the experimental results for brittle material. The damage zone and crack propagation path captured by the present method is compared with the experimental results (Chitrala et al. in J

Journal of Rock Mechanics and Geotechnical Engineering, 2011

In recent years, there are growing demands of representing rock mechanics and rock engineering in... more In recent years, there are growing demands of representing rock mechanics and rock engineering in a digital format that can be easily managed, manipulated, analyzed and shared. The objective of this paper is to give a comprehensive review of the status quo and future trends of digitization in rock mechanics and rock engineering. Research topics essential to the process of digitization are firstly discussed, including data acquisition, data standardization, geological modeling, visualization and digital-numerical integration. New techniques that will play an important role in digitization process but require further improvement are then briefly proposed. Finally, achievements of present methods and techniques for digitization in substantial rock mechanics and rock engineering are presented.

Scientific Reports, 2013

We investigate the thermal conductivity in the armchair and zigzag MoS 2 nanoribbons, by combinin... more We investigate the thermal conductivity in the armchair and zigzag MoS 2 nanoribbons, by combining the non-equilibrium Green's function approach and the first-principles method. A strong orientation dependence is observed in the thermal conductivity. Particularly, the thermal conductivity for the armchair MoS 2 nanoribbon is about 673.6 Wm 21 K 21 in the armchair nanoribbon, and 841.1 Wm 21 K 21 in the zigzag nanoribbon at room temperature. By calculating the Caroli transmission, we disclose the underlying mechanism for this strong orientation dependence to be the fewer phonon transport channels in the armchair MoS 2 nanoribbon in the frequency range of [150, 200] cm 21. Through the scaling of the phonon dispersion, we further illustrate that the thermal conductivity calculated for the MoS 2 nanoribbon is esentially in consistent with the superior thermal conductivity found for graphene.

Batteries

Recently, benzotrithiophene graphdiyne (BTT-GDY), a novel two-dimensional (2D) carbon-based mater... more Recently, benzotrithiophene graphdiyne (BTT-GDY), a novel two-dimensional (2D) carbon-based material, was grown via a bottom-up synthesis strategy. Using the BTT-GDY lattice and by replacing the S atoms with N, NH and O, we designed three novel GDY lattices, which we named BTHP-, BTP- and BTF-GDY, respectively. Next, we explored structural, electronic, mechanical, optical, photocatalytic and Li-ion storage properties, as well as carrier mobilities, of novel GDY monolayers. Phonon dispersion relations, mechanical and failure behavior were explored using the machine learning interatomic potentials (MLIPs). The obtained HSE06 results reveal that BTX-GDYs (X = P, F, T) are direct gap semiconductors with band gaps in the range of 2.49–2.65 eV, whereas the BTHP-GDY shows a narrow indirect band gap of 0.06 eV. With appropriate band offsets, good carrier mobilities and a strong capability for the absorption of visible and ultraviolet range of light, BTF- and BTT-GDYs were predicted to be pr...

Computational methods in engineering & the sciences, 2023

We present a general finite deformation higher-order gradient elasticity theory. The governing eq... more We present a general finite deformation higher-order gradient elasticity theory. The governing equations of the higher-order gradient solid along with boundary conditions of various orders are derived from a variational principle using integration by parts on the surface. The objectivity of the energy functional is achieved by carefully selecting the invariants under rigid-body transformation. The third-order gradient solid theory includes more than 10.000 material parameters. However, under certain simplifications, the material parameters can be greatly reduced; down to 3. With this simplified formulation, we develop a nonlocal operator method and apply it to several numerical examples. The numerical analysis shows that the high gradient solid theory exhibits a stiffer response compared to a 'conventional' hyperelastic solid. The numerical tests also demonstrate the capability of the nonlocal operator method in solving higher-order physical problems.

Computational methods in engineering & the sciences, 2023

In this paper we develop a new Peridynamic approach that naturally includes varying horizon sizes... more In this paper we develop a new Peridynamic approach that naturally includes varying horizon sizes and completely solves the "ghost force" issue. Therefore, the concept of dual-horizon is introduced to consider the unbalanced interactions between the particles with different horizon sizes. The present formulation is proved to fulfill both the balances of linear momentum and angular momentum. Neither the "partial stress tensor" nor the "'slice" technique are needed to ameliorate the ghost force issue in [1]. The consistency of reaction forces is naturally fulfilled by a unified simple formulation. The method can be easily implemented to any existing peridynamics code with minimal changes. A simple adaptive refinement procedure is proposed minimizing the computational cost. The method is applied here to the three Peridynamic formulations, namely bond based, ordinary state based and nonordinary state based Peridynamics. Both two-and three-dimensional examples including the Kalthof-Winkler experiment and plate with branching cracks are tested to demonstrate the capability of the method in solving wave propagation, fracture and adaptive analysis .

Coatings

In the latest ground-breaking experimental advancement (Nature (2022), 606, 507), zero-dimensiona... more In the latest ground-breaking experimental advancement (Nature (2022), 606, 507), zero-dimensional fullerenes (C60) have been covalently bonded to form single-layer two-dimensional (2D) fullerene network, namely quasi-hexagonal-phase fullerene (qHPC60). Motivated by the aforementioned accomplishment, in this communication, for the first time, we explore the phononic and mechanical properties of the qHPC60 monolayer, employing state-of-the-art machine-learning interatomic potentials. By employing an efficient passive-training methodology, the thermal and mechanical properties were examined with an ab-initio level of accuracy using the classical molecular dynamics simulations. Predicted phonon dispersion confirmed the desirable dynamical stability of the qHPC60 monolayer. Room temperature lattice thermal conductivity is predicted to be ultralow and around 2.9 (5.7) W/m·K along the x(y) directions, which are by three orders of magnitude lower than that of the graphene. Close to the gro...

Advanced Energy Materials

Accurate examination of electricity generation stemming from higher‐order deformation (flexoelect... more Accurate examination of electricity generation stemming from higher‐order deformation (flexoelectricity) in 2D layered materials is a highly challenging task to be investigated with either conventional computational or experimental tools. To address this challenge herein an innovative and computationally efficient approach on the basis of density functional theory (DFT) and machine‐learning interatomic potentials (MLIPs) with incorporated long‐range interactions to accurately investigate the flexoelectric energy conversion in 2D van der Waals (vdW) bilayers is proposed. In this approach, short‐range interactions are accurately defined using the moment tensor potentials trained over computationally inexpensive DFT‐based datasets. The long‐range electrostatic (charge and dipole) and vdW interaction parameters are calibrated from DFT simulations. Elaborated comparison of mechanical and piezoelectric properties extracted from the herein proposed approach with available data confirms the...

FlatChem, 2021

In a latest experimental advance, graphene-like and insulating BeO monolayer was successfully gro... more In a latest experimental advance, graphene-like and insulating BeO monolayer was successfully grown over silver surface by molecular beam epitaxy (ACS Nano 15(2021), 2497). Inspired by this accomplishment, in this work we conduct first-principles based simulations to explore the electronic, mechanical properties and thermal conductivity of graphene-like BeO, MgO and CaO monolayers. The considered nanosheets are found to show desirable thermal and dynamical stability. BeO monolayer is found to show remarkably high elastic modulus and tensile strength of 408 and 53.3 GPa, respectively. The electronic band gap of BeO, MgO and CaO monolayers are predicted to be 6.72, 4.79, and 3.80 eV, respectively, using the HSE06 functional. On the basis of iterative solutions of the Boltzmann transport equation, the room temperature lattice thermal conductivity of BeO, MgO and CaO monolayers are predicted to be 385, 64 and 15 W/mK, respectively. Our results reveal substantial decline in the electronic band gap, mechanical strength and thermal conductivity by increasing the weight of metal atoms. This work highlights outstandingly high thermal conductivity, carrier mobility and mechanical strength of insulating BeO nanosheets and suggest them as promising candidates to design strong and insulating components with high thermal conductivities.

Materials Today Nano, 2021

Beryllium polynitrides, BeN4 is a novel layered material, which has been most recently fabricated... more Beryllium polynitrides, BeN4 is a novel layered material, which has been most recently fabricated under high pressure (Phys. Rev. Lett. 126(2021), 175501). As a new class of 2D materials, in this work we conduct first-principles calculations to examine the stability and explore the electronic nature of MN4 (M= Be, Mg, Ir, Rh, Ni, Cu, Au, Pd, Pt) monolayers. Acquired results confirm the dynamical and thermal stability of BeN4, MgN4, IrN4, PtN4 and RhN4 monolayers. Interestingly, BeN4 and MgN4 monolayers are found to show anisotropic Dirac cones in their electronic structure. While PtN4 monolayer is predicted to be a narrow band-gap semiconductor, IrN4 and RhN4 monolayers are found to be metallic systems. We also elaborately explore the effects of number of atomic layers on the electronic features of BeN4 nanosheets, which reveal highly appealing physics. Our results highlight that BeN4 nanosheet yield ultrahigh elastic modulus and mechanical strength, outperforming all other carbon-free 2D materials. Notably, RhN4 nanosheet is predicted to yield high capacities of 562, 450 and 900 mAh/g, for Li, Na and Ca ions storages, respectively. This study provides a comprehensive understanding on the intrinsic properties of MN4 nanosheets and highlight their outstanding physics.

Carbon, 2021

Examination of thermal expansion of two-dimensional (2D) nanomaterials is a challenging theoretic... more Examination of thermal expansion of two-dimensional (2D) nanomaterials is a challenging theoretical task with either ab-initio or classical molecular dynamics simulations. In this regard, while ab-initio molecular dynamics (AIMD) simulations offer extremely accurate predictions, but they are excessively demanding from computational point of view. On the other side, classical molecular dynamics simulations can be conducted with affordable computational costs, but without predictive accuracy needed to study novel materials and compositions. Herein, we explore the thermal expansion of several carbon-based nanosheets on the basis of machine-learning interatomic potentials (MLIPs). We show that passively trained MLIPs over inexpensive AIMD trajectories enable the examination of thermal expansion of complex nanomembranes over wide range of temperatures. Passively fitted MLIPs could also with outstanding accuracy reproduce the phonon dispersion relations predicted by density functional theory calculations. Our results highlight that the devised methodology on the basis of passively trained MLIPs is computationally efficient and versatile to accurately examine the thermal expansion of complex and novel materials and compositions using the molecular dynamics simulations.

Carbon, 2020

Carbon nitride two-dimensional (2D) materials are among the most attractive class of nanomaterial... more Carbon nitride two-dimensional (2D) materials are among the most attractive class of nanomaterials, with wide range of application prospects. As a continuous progress, most recently, two novel carbon nitride 2D lattices of C 3 N 5 and C 3 N 4 have been successfully experimentally realized. Motivated by these latest accomplishments and also by taking into account the well-known C 3 N 4 triazine-based graphitic carbon nitride structures, we predicted two novel C 3 N 6 and C 3 N 4 counterparts. We then conducted extensive density functional theory simulations to explore the thermal stability, mechanical, electronic and optical properties of these novel nanoporous carbon-nitride nanosheets. According to our results all studied nanosheets were found to exhibit desirable thermal stability and mechanical properties. Non-equilibrium molecular dynamics simulations on the basis of machine learning interatomic potentials predict ultralow thermal conductivities for these novel nanosheets. Electronic structure analyses confirm direct band gap semiconducting electronic character and optical calculations reveal the ability of these novel 2D systems to adsorb visible range of light. Extensive first-principles based results by this study provide a comprehensive vision on the stability, mechanical, electronic and optical responses of C 3 N 4 , C 3 N 5 and C 3 N 6 as novel 2D semiconductors and suggest them as promising candidates for the design of advanced nanoelectronics and energy storage/conversion systems.

Applied Physics A, 2021

In this work, extensive reactive molecular dynamics simulations are conducted to analyze the nano... more In this work, extensive reactive molecular dynamics simulations are conducted to analyze the nanopore creation by nanoparticles impact over single-layer molybdenum disulfide (MoS2) with 1T and 2H phases. We also compare the results with graphene monolayer. In our simulations, nanosheets are exposed to a spherical rigid carbon projectile with high initial velocities ranging from 2 to 23 km/s. Results for three different structures are compared to examine the most critical factors in the perforation and resistance force during the impact. To analyze the perforation and impact resistance, kinetic energy and displacement time history of the projectile as well as perforation resistance force of the projectile are investigated. Interestingly, although the elasticity module and tensile strength of the graphene are by almost five times higher than those of MoS2, the results demonstrate that 1T and 2H-MoS2 phases are more resistive to the impact loading and perforation than graphene. For the...

Materials Horizons, 2020

We highlight that machine-learning interatomic potentials trained over short AIMD trajectories en... more We highlight that machine-learning interatomic potentials trained over short AIMD trajectories enable first-principles multiscale modeling, bridging DFT level accuracy to the continuum level and empowering the study of complex/novel nanostructures.

Applied Materials Today, 2020

Phononic properties are commonly studied by calculating force constants using the density functio... more Phononic properties are commonly studied by calculating force constants using the density functional theory (DFT) simulations. Although DFT simulations offer accurate estimations of phonon dispersion relations or thermal properties, but for low-symmetry and nanoporous structures the computational cost quickly becomes very demanding. Moreover, the computational setups may yield nonphysical imaginary frequencies in the phonon dispersion curves, impeding the assessment of phononic properties and the dynamical stability of the considered system. Here, we compute phonon dispersion relations and examine the dynamical stability of a large ensemble of novel materials and compositions. We propose a fast and convenient alternative to DFT simulations which derived from machine-learning interatomic potentials passively trained over computationally efficient ab-initio molecular dynamics trajectories. Our results for diverse two-dimensional (2D) nanomaterials confirm that the proposed computational strategy can reproduce fundamental thermal properties in close agreement with those obtained via the DFT approach. The presented method offers a stable, efficient, and convenient solution for the examination of dynamical stability and exploring the phononic properties of low-symmetry and porous 2D materials.

Journal of Materials Chemistry C, 2020

Mechanical response, dynamical/thermal stability, electronic/optical properties and photocatalyti... more Mechanical response, dynamical/thermal stability, electronic/optical properties and photocatalytic features of monoclinic As2X3 (X = S, Se and Te) nanosheets are explored via DFT simulations. As2Te3 lattice predicted by this study is found to exhibit superior superstretchability, outperforming other known 2D materials.

Coatings, 2019

Group IV–V-type layered materials, such as SiP, SiAs, GeP and GeAs, are among the most attractive... more Group IV–V-type layered materials, such as SiP, SiAs, GeP and GeAs, are among the most attractive two-dimensional (2D) materials that exhibit anisotropic mechanical, optical and transport properties. In this short communication, we conducted density functional theory simulations to explore the prospect of SiP, SiAs, GeP and GeAs nanosheets for the water-splitting application. The semiconducting gaps of stress-free SiP, SiAs, GeP and GeAs monolayers were estimated to be 2.59, 2.34, 2.30 and 2.07 eV, respectively, which are within the desirable ranges for the water splitting. Moreover, all the considered nanomaterials were found to yield optical absorption in the visible spectrum, which is a critical feature for the employment in the solar water splitting systems. Our results furthermore confirm that the valence and conduction band edge positions in SiP, SiAs, GeP and GeAs monolayers also satisfy the requirements for the water splitting. Our results highlight the promising photocataly...

Underground Space, 2018

In this study, we present an adaptive phase field method (APFM) for modeling quasi-static crack p... more In this study, we present an adaptive phase field method (APFM) for modeling quasi-static crack propagation in rocks. Crack initiation due to positive strains is considered, and a numerical simulation is implemented using a commercial software, COMSOL Multiphysics. Two benchmark tests are first examined, namely, a single-edge-notched square plate subjected to respective tension and shear loadings. The crack propagation in Brazil splitting tests, 2D notched semi-circular bend (NSCB) tests, and 3D NSCB tests are subsequently simulated and analyzed. All the numerical examples indicate that the propagation of the cracks is autonomous and external fracture criteria are not required for phase field modeling. Furthermore, the adaptive remeshing scheme reduces unnecessary global mesh refinement and exhibits good adaptability for fracture modeling. The simulations are in good agreement with the experimental observations, and thereby indicate the feasibility and practicability of the APFM in rocks (even in 3D cases).

Materials (Basel, Switzerland), Jan 31, 2018

An amorphous polyethylene/silica (PE/S) interface exists in many materials. However, the research... more An amorphous polyethylene/silica (PE/S) interface exists in many materials. However, the research of the interfacial properties at microscale is lacking. Shear failure and adhesion properties of an amorphous PE/S interface are studied by molecular dynamics. The effects of PE chain length, the number of chains, and coupling agents on the shear behavior and interfacial adhesion are investigated. It is found that the modified silica (mS) surface induces an increase in the adhesion strength compared to unmodified S. The damage process and failure mode of the PE/S and PE/mS interface are analyzed at microscale. The contribution of bond length, bond angle, torsional potentials, and nonbonded energy is estimated as a function of the shear deformation to clarify the deformation mechanisms. The energy partitioning results indicate that the elastic, yield, and postyielding regions are mostly controlled by the nonbonded interactions. The dihedral motions of the chains also have an influence. F...

International Journal of Fracture, 2016

A multiscale computational homogenization method for the modeling of hydro-mechanical coupling pr... more A multiscale computational homogenization method for the modeling of hydro-mechanical coupling problem for quasi-brittle materials is developed. The present method is based on an asymptotic expansion homogenization combined with the semiconcurrent finite element modelling approach. Modified periodic boundary conditions and a molecular dynamics (MD) based inclusion or filler generation procedure are devised for the hydro-mechanical coupling problem. A modified elastic damage constitutive model and a damage induced permeability law have been developed for the hydraulic fracturing. The statistical convergence of the microscale representative volume element (RVE) model regarding the RVE characteristic size is studied. It was found that the RVE characteristic size is determined by both the mechanical and hydraulic properties of the RVE simultaneously. The present method is validated by the experimental results for brittle material. The damage zone and crack propagation path captured by the present method is compared with the experimental results (Chitrala et al. in J

Journal of Rock Mechanics and Geotechnical Engineering, 2011

In recent years, there are growing demands of representing rock mechanics and rock engineering in... more In recent years, there are growing demands of representing rock mechanics and rock engineering in a digital format that can be easily managed, manipulated, analyzed and shared. The objective of this paper is to give a comprehensive review of the status quo and future trends of digitization in rock mechanics and rock engineering. Research topics essential to the process of digitization are firstly discussed, including data acquisition, data standardization, geological modeling, visualization and digital-numerical integration. New techniques that will play an important role in digitization process but require further improvement are then briefly proposed. Finally, achievements of present methods and techniques for digitization in substantial rock mechanics and rock engineering are presented.

Scientific Reports, 2013

We investigate the thermal conductivity in the armchair and zigzag MoS 2 nanoribbons, by combinin... more We investigate the thermal conductivity in the armchair and zigzag MoS 2 nanoribbons, by combining the non-equilibrium Green's function approach and the first-principles method. A strong orientation dependence is observed in the thermal conductivity. Particularly, the thermal conductivity for the armchair MoS 2 nanoribbon is about 673.6 Wm 21 K 21 in the armchair nanoribbon, and 841.1 Wm 21 K 21 in the zigzag nanoribbon at room temperature. By calculating the Caroli transmission, we disclose the underlying mechanism for this strong orientation dependence to be the fewer phonon transport channels in the armchair MoS 2 nanoribbon in the frequency range of [150, 200] cm 21. Through the scaling of the phonon dispersion, we further illustrate that the thermal conductivity calculated for the MoS 2 nanoribbon is esentially in consistent with the superior thermal conductivity found for graphene.