Molecular crystals are complex systems exhibiting various crystal structures,and accurately modeling the crystal structures is essential for understanding their physical behaviors under high pressure.Here,we perform a...Molecular crystals are complex systems exhibiting various crystal structures,and accurately modeling the crystal structures is essential for understanding their physical behaviors under high pressure.Here,we perform an extensive structure search of ternary carbon-nitrogen-oxygen(CNO)compound under high pressure with the CALYPSO method and first principles calculations,and successfully identify three polymeric CNO compounds with Pbam,C2/m and I4m2symmetries under 100 GPa.More interestingly,these structures are also dynamically stable at ambient pressure,and are potential high energy density materials(HEDMs).The energy densities of Pbam,C2/m and I4m2 phases of CNO are about2.30 kJ/g,1.37 kJ/g and 2.70 kJ/g,respectively,with the decompositions of graphitic carbon and molecular carbon dioxide andα-N(molecular N_(2))at ambient pressure.The present results provide in-depth insights into the structural evolution and physical properties of CNO compounds under high pressures,which offer crucial insights for designs and syntheses of novel HEDMs.展开更多
Based on the lowest melting point and Schroeder’s theoretical calculation formula,nano- modified organic composite phase change materials（PCMs）were prepared.The phase transition temperature and the latent heat of t...Based on the lowest melting point and Schroeder’s theoretical calculation formula,nano- modified organic composite phase change materials（PCMs）were prepared.The phase transition temperature and the latent heat of the materials were 24℃and 172 J/g,respectively.A new shape-stabilized phase change materials were prepared,using high density polyethylene as supporting material.The PCM kept the shape when temperature was higher than melting point.Thus,it can directly contact with heat transfer media.The structure,morphology and thermal behavior of PCM were analyzed by FTIR,SEM and DSC.展开更多
Since the seminal work by Kojima et al. in 2009, solar cells based on hybrid organic-inorganic perovskites have attracted considerable attention and experienced an exponential growth, with photovoltaic efficiencies as...Since the seminal work by Kojima et al. in 2009, solar cells based on hybrid organic-inorganic perovskites have attracted considerable attention and experienced an exponential growth, with photovoltaic efficiencies as of today reaching above 22%. Despite such an impressive development, some key scientific issues of these materials, including the presence of toxic lead, the poor long-term device stability under heat and humidity conditions, and the anomalous hysteresis of the current-voltage curves shown by various solar cell devices, still remain unsolved and constitute an important focus of experimental and theoretical researchers throughout the world. Density functional theory calculations have been successfully applied to exploring structural and electronic properties of semiconductors, complementing the experimental results in search and discovery of novel functional materials. In this review, we summarize the current progress in perovskite photovoltaic materials from a theoretical perspective. We discuss design of lead-free perovskite materials, humidity-induced degradation mechanisms and possible origins for the observed solar cell hysteresis, and assess future research directions for advanced perovskite solar cells based on computational materials design and theoretical understanding of intrinsic properties.展开更多
We implemented the process of producing a new Rib in three different ways, and we selected the process that was the most affordable and required the least labor, and we did it. This paper also considers the influence ...We implemented the process of producing a new Rib in three different ways, and we selected the process that was the most affordable and required the least labor, and we did it. This paper also considers the influence of the cost of the form from MDF, Alumina and Steel on the quality of the product.展开更多
CONSPECTUS:In this Account,we present a comprehensive overview of recent advancements in applying data-driven combinatorial design for developing novel highenergy-density materials.Initially,we outline the progress in...CONSPECTUS:In this Account,we present a comprehensive overview of recent advancements in applying data-driven combinatorial design for developing novel highenergy-density materials.Initially,we outline the progress in energetic materials(EMs)development within the framework of the four scientific paradigms,with particular emphasis on the opportunities afforded by the evolution of computer and data science,which has propelled the theoretical design of EMs into a new era of data-driven development.We then discuss the structural features of typical EMs such as TNT,RDX,HMX,and CL-20,namely,a“scaffolds+functional groups”characteristic,underscoring the efficacy of the combinatorial design approach in constructing novel EMs.It has been discerned that those modifications to the scaffolds are the primary driving force behind the enhancement of EMs’properties.Subsequently,we introduce three distinct data-driven design strategies for EMs,each with a different approach to scaffold construction.These strategies are as follows:(1)the known scaffold strategy to identify fused cyclic scaffolds containing oxazole or oxadiazole structures from other fields via database screening and employ a high-throughput combinatorial approach with functional groups to design oxazole(and oxadiazole)-based fused cyclic EMs;(2)the semiknown scaffold strategy to construct semiknown scaffolds by integrating known scaffolds and realize the design of bridged cyclic EMs through a high-throughput combination of functional groups;(3)the unknown scaffold strategy to build caged structural models for quantitative characterization,high-throughput screening caged scaffolds from the database,construct unknown caged scaffolds by substituting atoms or substructures,and combine functional groups to design zero oxygen balance caged EMs.Employing the proposed strategies,the design capacity for EMs reaches an impressive scale of 10^(7) molecules,significantly increasing the probability of obtaining high-performance EMs.Furthermore,the incorporation of property assessment models based on machine learning and density functional theory has achieved a balance between computational accuracy and computational speed.Statistical analysis of the virtual screening has revealed the advantages of bicyclic tri-and tetrasubstituted position scaffolds in the construction of high-energy and easily synthesizable fused cyclic EMs.Additionally,the proposed strategies have been successfully applied to design multifunctional modular energetic materials,resulting in the successful synthesis of three target compounds,validating the effectiveness of data-driven combinatorial design approaches.Lastly,we discuss the current state of high-throughput combinatorial design and,in light of the multifaceted criteria required for the design of EMs,explore the feasibility of multiobjective optimization methods such as Pareto optimization.Moreover,we envision the application of generative models in the subsequent design and development of EMs.We anticipate that this Account will provide valuable insights into the theoretical design of EMs,and we envision the integration of new technologies and methodologies that could play an increasingly significant role in the future discovery of EMs.展开更多
A novel cuprous azide complex with the formula of [Cu2（dmpz）（N3）2]n（1, dmpz： 2,6-dimethylpyrazine） has been synthesized through hydrothermal synthesis with the reducibility of H3PO3 and structurally characteriz...A novel cuprous azide complex with the formula of [Cu2（dmpz）（N3）2]n（1, dmpz： 2,6-dimethylpyrazine） has been synthesized through hydrothermal synthesis with the reducibility of H3PO3 and structurally characterized by single-crystal X-ray diffraction method. Single-crystal X-ray diffraction analysis reveals the title complex represents a three-dimensional network structure featuring 2D [Cu N3]n plane units bridged by bridging dmpz ligands to form a 3D network. Research results reveal that 1 has lower impact sensitivity and friction sensitivity, which may be expected to become insensitive energetic material and have potential applications. Crystal data： monoclinic, space group C2/c, a = 17.8599（15）, b = 8.2889（5）, c = 14.8076（14） A, β = 113.2580（10）o, V = 2014.0（3） A3, Z = 8, S = 1.025, the final R = 0.0303, w R = 0.0825 for 1460 observed reflections with I 2σ（I） and R = 0.0386, wR = 0.0870 for all reflections. In addition, elemental analysis, IR, and sensitivity characterization are presented.展开更多
Geometries, energies, and vibrational frequencies for two C4N12O4 isomers with pagodane- and isopagodane-like structures have been calculated at the B3LYP/6-31G＊ level.Isomers 1 and 2 are of D2h and D2d symmetry, res...Geometries, energies, and vibrational frequencies for two C4N12O4 isomers with pagodane- and isopagodane-like structures have been calculated at the B3LYP/6-31G＊ level.Isomers 1 and 2 are of D2h and D2d symmetry, respectively. Heats of formation for the two C4N12O4 isomers have been estimated in this paper, indicating they would be reasonable candidates for high energy density materials.展开更多
Based on the full optimized molecular geometric structure at 6-311＋＋G＊＊ level,the density（ρ）,detonation velocity（D）,and detonation pressure（P） for a new furazan-based energetic macrocycle compound,hexakis[1...Based on the full optimized molecular geometric structure at 6-311＋＋G＊＊ level,the density（ρ）,detonation velocity（D）,and detonation pressure（P） for a new furazan-based energetic macrocycle compound,hexakis[1,2,5]oxadi-azole[3,4-c：3＇,4＇-e;3＇＇,4＇＇-g：3＇＇＇,4＇＇＇-k：3＇＇＇＇,4＇＇＇＇-m：3＇＇＇＇＇,4＇＇＇＇＇-o][1,2,9,10]-tetraazacyclohexadecine,were investigated to verify its capacity as high energy density material（HEDM）. The infrared spectrum was also predicted. The heat of formation（HOF） was calculated using designed isodesmic reaction. The calculation on the bond dissociation energies（BDEs） was done and the pyrolysis mechanism of the compound was studied. The result shows that the N3–O1 bond in the ring may be the weakest one and the ring cleavage is possible to happen in thermal decomposition. The condensed phase HOF and the crystal density were also calculated for the title compound. The detonation data show that it can be considered as a potential HEDM. These results would provide basic information for the molecular design of novel high energy materials.展开更多
Amorphous carbon materials play a vital role in adsorbed natural gas(ANG) storage. One of the key issues in the more prevalent use of ANG is the limited adsorption capacity, which is primarily determined by the porosi...Amorphous carbon materials play a vital role in adsorbed natural gas(ANG) storage. One of the key issues in the more prevalent use of ANG is the limited adsorption capacity, which is primarily determined by the porosity and surface characteristics of porous materials. To identify suitable adsorbents, we need a reliable computational tool for pore characterization and, subsequently, quantitative prediction of the adsorption behavior. Within the framework of adsorption integral equation(AIE), the pore-size distribution(PSD) is sensitive to the adopted theoretical models and numerical algorithms through isotherm fitting. In recent years, the classical density functional theory(DFT) has emerged as a common choice to describe adsorption isotherms for AIE kernel construction. However,rarely considered is the accuracy of the mean-field approximation(MFA) commonly used in commercial software. In this work, we calibrate four versions of DFT methods with grand canonical Monte Carlo(GCMC) molecular simulation for the adsorption of CH_4 and CO_2 gas in slit pores at 298 K with the pore width varying from 0.65 to 5.00 nm and pressure from 0.2 to 2.0 MPa. It is found that a weighted-density approximation proposed by Yu(WDA-Yu) is more accurate than MFA and other non-local DFT methods. In combination with the trapezoid discretization of AIE, the WDA-Yu method provides a faithful representation of experimental data, with the accuracy and stability improved by 90.0% and 91.2%, respectively, in comparison with the corresponding results from MFA for fitting CO_2 isotherms. In particular, those distributions in the feature pore width range(FPWR)are proved more representative for the pore-size analysis. The new theoretical procedure for pore characterization has also been tested with the methane adsorption capacity in seven activated carbon samples.展开更多
To further test whether polynitriprismanes are capable of being potential high energy density materials （HEDMs）, extensive theoretical calculations were carried out to investigate on a series of polynitrotriprisman...To further test whether polynitriprismanes are capable of being potential high energy density materials （HEDMs）, extensive theoretical calculations were carried out to investigate on a series of polynitrotriprismanes （PNNPs）： C6H6-.（NO2）. （n=1-6） Heats of formation （HOFs）, strain energies （SE）, and disproportionation energy （DE） were obtained using B3LYP/6-311＋G（2df, 2p）//B3LYP/6-31G＊ method by designing different isodesmic reactions, respectively. Detonation properties of PNNPs were obtained by the well-known KAMLET-JACOBS equations, using the predicted densities （p） obtained by Monte Carlo method and HOFs. It is found that they increase as the number of nitro groups n varies from 1 to 6, and PNNPs with n〉4 have excellent detonation properties The relative stability and the pyrolysis mechanism of PNNPs were evaluated by the calculated bond dissociation energy （BDE）. The comparison of BDE suggests that rupturing the C--C bond is the trigger for thermolysis of PNNPs. The computed BDE for cleavage of C--C bond （88.5 kJ/mol） further demonstrates that only the hexa-nitrotriprismane can be considered to be the target of HEDMs.展开更多
The cyclo-N_(6)anion is a total nitrogen unit with higher nitrogen content than cyclo-N^(-)_(5).However,the low decomposition barrier of cyclo-N_(6)anions hinders its application as a high energy density material(HEDM...The cyclo-N_(6)anion is a total nitrogen unit with higher nitrogen content than cyclo-N^(-)_(5).However,the low decomposition barrier of cyclo-N_(6)anions hinders its application as a high energy density material(HEDM).Using first-principles calculations,we reveal that the covalent components that enhance the interaction between the cyclo-N_(6)anion and the cation can effectively improve the stability of cyclo-N_(6)anions.The actinide metals(Th,Pa,U)are selected as suitable cations.Further electronic structure analysis showed that the charge transfer from the actinide metal to cyclo-N_(6)anions resulted in a strong covalent bond,which promoted the stability of the cyclo-N_(6)anion in the Th(N_(6)),Pa(N_(6)),and U(N_(6))structure.This discovery is helpful for the rational design and synthesis of new HEDMs.展开更多
The search for high energy density materials(HEDMs)in polymeric nitrogen compounds has gained considerable attention.Previous theoretical predictions and experiments have revealed that metal ions can be used to stabil...The search for high energy density materials(HEDMs)in polymeric nitrogen compounds has gained considerable attention.Previous theoretical predictions and experiments have revealed that metal ions can be used to stabilize the pentazolate(N-5)anion.In this work,by employing a machine learning-accelerated crystal structure searching method and first-principles calculations,we found that the new pentazolate salts,CaN(10)and BaN(10),are energetically favorable at high pressures.Phonon dispersion calculations reveal that they are quenchable at ambient pressure.Ab initio molecular dynamics simulations verify their dynamic stability at finite temperature.Bader charge and electron localization function illustrates that alkaline earth atoms serve as electron donors,contributing to the stability of N5 rings.Bonding calculations reveal covalent bonds between nitrogen atoms and weak interactions between N5 rings.Similar to other pentazolate salts,these polymeric nitrides have high energy densities of approximately 2.35 kJ/g for CaN(10)and 1.32 kJ/g for BaN(10).The predictions of CaN(10)and BaN(10)structures indicate that these salts are potential candidates for green nitrogen-rich HEDMs.展开更多
The geometric and electronic structures of the derivatives of 4-nitro-5-(5-nitroimino-1,2,4-triazol-3-yl)-2H-1,2,3-triazolate(named A~J)are explored employing density functional theory(DFT)calculations at the B3LYP/6-...The geometric and electronic structures of the derivatives of 4-nitro-5-(5-nitroimino-1,2,4-triazol-3-yl)-2H-1,2,3-triazolate(named A~J)are explored employing density functional theory(DFT)calculations at the B3LYP/6-311G^(**)level of theory.Based on the optimized molecular structures,the heats of formation(HOF)are obtained,and the electronic properties,density and molecular sensitivity by characteristic heights(H_(50))are discussed.Besides,the detonation performances(detonation velocity,detonation pressure)are estimated via Kamlet-Jacobs(K-J)formula.Compounds B(H50=29.4 cm,ρ=1.91 g/cm^(3),Q=1563.04 cal/g,P=36.05 GPa,D=8.95 km/s)and H(H_(50)=31.9 cm,ρ=1.80 g/cm^(3),Q=1610.09 cal/g,P=37.31 GPa,D=9.12 km/s)have positive HOFs and remarkable insensitivity and good detonation performance,strongly suggesting them as the acceptable new-type explosive.The initiating power surpasses conventional primary explosives,such as HMX.The outstanding detonation power of compounds B and H contributes to its future prospects as a promising green primary explosive.展开更多
In recent decades,pentazolate salts have gained considerable attention as high energy density materials(HEDMs).Using the machine-learning accelerated structure searching method,we predicted four pentazolate salts stab...In recent decades,pentazolate salts have gained considerable attention as high energy density materials(HEDMs).Using the machine-learning accelerated structure searching method,we predicted four pentazolate salts stabilized with tetravalent metals(Ti-N and Zr-N).Specifically,the ground state MN_(20)(M=Ti,Zr)adopts the space-group P 4/mcc under ambient conditions,transforming into the I-4 phase at higher pressure.Moreover,the I-4-MN_(20)becomes energetically stable at moderate pressure(46.8 GPa for TiN_(20),38.7 GPa for ZrN_(20)).Anharmonic phonon spectrum calculations demonstrate the dynamic stabilities of these MN_(20)phases.Among them,the P 4/mcc phase can be quenched to 0 GPa.Further ab-initio molecular dynamic simulations suggest that the N_(5)rings within these MN_(20)systems can still maintain integrity at finite temperatures.Calculations of the projected crystal orbital Hamilton population and reduced density gradient revealed their covalent and noncovalent interactions,respectively.The aromaticity of the N_(5)ring was investigated by molecular orbital theory.Finally,we predicted that these MN_(20)compounds have very high energy densities and exhibit good detonation velocities and pressures,compared to the HMX explosive.These calculations enrich the family of pentazolate compounds and may also guide future experiments.展开更多
This paper presents a numerical study of the hydroelastic coupling during the free-surface water entry of deformable spheres of different material densities.The focus is on the hydrodynamic forces,the stress loads,the...This paper presents a numerical study of the hydroelastic coupling during the free-surface water entry of deformable spheres of different material densities.The focus is on the hydrodynamic forces,the stress loads,the sphere deformations,the wetted areas of the sphere and the cavity dynamics,including the impacting of the elastic spheres and the hydroelastic coupled behaviors in the free surface flows.It is shown that the elastic wave propagation in the sphere scales with the sphere density.For elastic spheres immersed in the water,the variation of the sphere deformations and its energy transformation mechanism are discussed.From the contact point positions of the cavity,it can be seen that the wetted area of the sphere is closely related with the sphere deformation.The first deformation cycle is a turning point in the relation between the wetted area and the sphere density.Based on the map of m*−ηsummarized in this work,the influence of the sphere deformation on the shape of the cavity can be roughly predicted from the material properties and the impact conditions.展开更多
Ninety-one nitro and hydroxyl derivatives of benzene were studied at the B3LYP/6-31G＊ level of density functional theory. Detonation properties were calculated using the Kamlet-Jacobs equation. Three candidates （pen...Ninety-one nitro and hydroxyl derivatives of benzene were studied at the B3LYP/6-31G＊ level of density functional theory. Detonation properties were calculated using the Kamlet-Jacobs equation. Three candidates （pentanitrophenol, pentanitrobenzene, and hexanitrobenzene） were recommended as potential high energy density compounds for their perfect detonation performances and reasonable stability. The pyrolysis mechanism was studied by analyzing the bond dissociation energy （BDE） and the activation energy （Ea） of hydrogen transfer （H--T） reaction for those with adjacent nitro and hydroxyl groups. The results show that Ea is much lower than BDEs of all bonds, so when there are adjacent nitro and hydroxyl groups in a molecule, the stability of the compound will decrease and the pyrolysis will be initiated by the H--T process. Otherwise, the pyrolysis will start from the breaking of the weakest C--NO2 bond, and only under such condition, the Mulliken population or BDE of the C--NO2 bond can be used to assess the relative stability of the compound.展开更多
Density functional theory (DFT) method has been employed to study the effect of nitroamino group as a substituent in cyclopentane and cyclohexane, which usually construct the polycyclic or caged nitra-mines. Molecular...Density functional theory (DFT) method has been employed to study the effect of nitroamino group as a substituent in cyclopentane and cyclohexane, which usually construct the polycyclic or caged nitra-mines. Molecular structures were investigated at the B3LYP/6-31G** level, and isodesmic reactions were designed for calculating the group interactions. The results show that the group interactions ac-cord with the group additivity, increasing with the increasing number of nitroamino groups. The dis-tance between substituents influences the interactions. Detonation performances were evaluated by the Kamlet-Jacobs equations based on the predicted densities and heats of formation, while thermal stability and pyrolysis mechanism were studied by the computations of bond dissociation energy (BDE). It is found that the contributions of nitroamino groups to the detonation heat, detonation velocity, detonation pressure, and stability all deviate from the group additivity. Only 3a, 3b, and 9a-9c may be novel potential candidates of high energy density materials (HEDMs) according to the quantitative cri-teria of HEDM (ρ ≈ 1.9 g/cm3, D ≈ 9.0 km/s, P ≈ 40.0 GPa). Stability decreases with the increasing number of N-NO2 groups, and homolysis of N-NO2 bond is the initial step in the thermolysis of the title com-pounds. Coupled with the demand of thermal stability (BDE > 20 kcal/mol), only 1,2,4-trinitrotriazacy-clohexane and 1,2,4,5-tetranitrotetraazacyclohexane are suggested as feasible energetic materials. These results may provide basic information for the molecular design of HEDMs.展开更多
基金the National Natural Science Foundation of China(Grant Nos.12174352 and 12111530103)the Fundamental Research Funds for the Central UniversitiesChina University of Geosciences(Wuhan)(Grant No.G1323523065)。
文摘Molecular crystals are complex systems exhibiting various crystal structures,and accurately modeling the crystal structures is essential for understanding their physical behaviors under high pressure.Here,we perform an extensive structure search of ternary carbon-nitrogen-oxygen(CNO)compound under high pressure with the CALYPSO method and first principles calculations,and successfully identify three polymeric CNO compounds with Pbam,C2/m and I4m2symmetries under 100 GPa.More interestingly,these structures are also dynamically stable at ambient pressure,and are potential high energy density materials(HEDMs).The energy densities of Pbam,C2/m and I4m2 phases of CNO are about2.30 kJ/g,1.37 kJ/g and 2.70 kJ/g,respectively,with the decompositions of graphitic carbon and molecular carbon dioxide andα-N(molecular N_(2))at ambient pressure.The present results provide in-depth insights into the structural evolution and physical properties of CNO compounds under high pressures,which offer crucial insights for designs and syntheses of novel HEDMs.
基金Funded by the National Key Technologies Research and Development Program of China(No.2006BAJ04A16)
文摘Based on the lowest melting point and Schroeder’s theoretical calculation formula,nano- modified organic composite phase change materials（PCMs）were prepared.The phase transition temperature and the latent heat of the materials were 24℃and 172 J/g,respectively.A new shape-stabilized phase change materials were prepared,using high density polyethylene as supporting material.The PCM kept the shape when temperature was higher than melting point.Thus,it can directly contact with heat transfer media.The structure,morphology and thermal behavior of PCM were analyzed by FTIR,SEM and DSC.
基金support of the National Natural Science Foundation of China,grant nos.21473183 and 21303079the Foundation for Polish Science,grant no.42.2016,for support through the START 2016 program+1 种基金US National Science Foundation,grant no.CHE-1565704US Department of Energy,grant no.DE-SC0014429,for financial support
文摘Since the seminal work by Kojima et al. in 2009, solar cells based on hybrid organic-inorganic perovskites have attracted considerable attention and experienced an exponential growth, with photovoltaic efficiencies as of today reaching above 22%. Despite such an impressive development, some key scientific issues of these materials, including the presence of toxic lead, the poor long-term device stability under heat and humidity conditions, and the anomalous hysteresis of the current-voltage curves shown by various solar cell devices, still remain unsolved and constitute an important focus of experimental and theoretical researchers throughout the world. Density functional theory calculations have been successfully applied to exploring structural and electronic properties of semiconductors, complementing the experimental results in search and discovery of novel functional materials. In this review, we summarize the current progress in perovskite photovoltaic materials from a theoretical perspective. We discuss design of lead-free perovskite materials, humidity-induced degradation mechanisms and possible origins for the observed solar cell hysteresis, and assess future research directions for advanced perovskite solar cells based on computational materials design and theoretical understanding of intrinsic properties.
文摘We implemented the process of producing a new Rib in three different ways, and we selected the process that was the most affordable and required the least labor, and we did it. This paper also considers the influence of the cost of the form from MDF, Alumina and Steel on the quality of the product.
基金support from National Natural Science Foundation of China(Nos.22275145 and 21875184)Natural Science Foundation of Shaanxi Province(Nos.2022JC-10 and 2024JC-YBQN-0112).
文摘CONSPECTUS:In this Account,we present a comprehensive overview of recent advancements in applying data-driven combinatorial design for developing novel highenergy-density materials.Initially,we outline the progress in energetic materials(EMs)development within the framework of the four scientific paradigms,with particular emphasis on the opportunities afforded by the evolution of computer and data science,which has propelled the theoretical design of EMs into a new era of data-driven development.We then discuss the structural features of typical EMs such as TNT,RDX,HMX,and CL-20,namely,a“scaffolds+functional groups”characteristic,underscoring the efficacy of the combinatorial design approach in constructing novel EMs.It has been discerned that those modifications to the scaffolds are the primary driving force behind the enhancement of EMs’properties.Subsequently,we introduce three distinct data-driven design strategies for EMs,each with a different approach to scaffold construction.These strategies are as follows:(1)the known scaffold strategy to identify fused cyclic scaffolds containing oxazole or oxadiazole structures from other fields via database screening and employ a high-throughput combinatorial approach with functional groups to design oxazole(and oxadiazole)-based fused cyclic EMs;(2)the semiknown scaffold strategy to construct semiknown scaffolds by integrating known scaffolds and realize the design of bridged cyclic EMs through a high-throughput combination of functional groups;(3)the unknown scaffold strategy to build caged structural models for quantitative characterization,high-throughput screening caged scaffolds from the database,construct unknown caged scaffolds by substituting atoms or substructures,and combine functional groups to design zero oxygen balance caged EMs.Employing the proposed strategies,the design capacity for EMs reaches an impressive scale of 10^(7) molecules,significantly increasing the probability of obtaining high-performance EMs.Furthermore,the incorporation of property assessment models based on machine learning and density functional theory has achieved a balance between computational accuracy and computational speed.Statistical analysis of the virtual screening has revealed the advantages of bicyclic tri-and tetrasubstituted position scaffolds in the construction of high-energy and easily synthesizable fused cyclic EMs.Additionally,the proposed strategies have been successfully applied to design multifunctional modular energetic materials,resulting in the successful synthesis of three target compounds,validating the effectiveness of data-driven combinatorial design approaches.Lastly,we discuss the current state of high-throughput combinatorial design and,in light of the multifaceted criteria required for the design of EMs,explore the feasibility of multiobjective optimization methods such as Pareto optimization.Moreover,we envision the application of generative models in the subsequent design and development of EMs.We anticipate that this Account will provide valuable insights into the theoretical design of EMs,and we envision the integration of new technologies and methodologies that could play an increasingly significant role in the future discovery of EMs.
基金Supported by the National Natural Science Foundation of China(No.21203160)Education Department Foundation of Shaanxi Province(No.12JK0631)+1 种基金Natural Science Foundation of Shaanxi Province(No.2013JM2013)Special Research Fund of Xianyang Normal University(No.11XSYK204,11XSYK205,12XSYK023)
文摘A novel cuprous azide complex with the formula of [Cu2（dmpz）（N3）2]n（1, dmpz： 2,6-dimethylpyrazine） has been synthesized through hydrothermal synthesis with the reducibility of H3PO3 and structurally characterized by single-crystal X-ray diffraction method. Single-crystal X-ray diffraction analysis reveals the title complex represents a three-dimensional network structure featuring 2D [Cu N3]n plane units bridged by bridging dmpz ligands to form a 3D network. Research results reveal that 1 has lower impact sensitivity and friction sensitivity, which may be expected to become insensitive energetic material and have potential applications. Crystal data： monoclinic, space group C2/c, a = 17.8599（15）, b = 8.2889（5）, c = 14.8076（14） A, β = 113.2580（10）o, V = 2014.0（3） A3, Z = 8, S = 1.025, the final R = 0.0303, w R = 0.0825 for 1460 observed reflections with I 2σ（I） and R = 0.0386, wR = 0.0870 for all reflections. In addition, elemental analysis, IR, and sensitivity characterization are presented.
基金This work was supported by the Natural Science Foundation of Shandong Province (Y2002G11)
文摘Geometries, energies, and vibrational frequencies for two C4N12O4 isomers with pagodane- and isopagodane-like structures have been calculated at the B3LYP/6-31G＊ level.Isomers 1 and 2 are of D2h and D2d symmetry, respectively. Heats of formation for the two C4N12O4 isomers have been estimated in this paper, indicating they would be reasonable candidates for high energy density materials.
基金supported by the National Natural Science Foundation of China(No.U1304111)the Program for Science&Technology Innovation Talents in Universities of Henan Province(No.14HASTIT039)the Innovation Team of Henan University of Science and Technology(2015XTD001)
文摘Based on the full optimized molecular geometric structure at 6-311＋＋G＊＊ level,the density（ρ）,detonation velocity（D）,and detonation pressure（P） for a new furazan-based energetic macrocycle compound,hexakis[1,2,5]oxadi-azole[3,4-c：3＇,4＇-e;3＇＇,4＇＇-g：3＇＇＇,4＇＇＇-k：3＇＇＇＇,4＇＇＇＇-m：3＇＇＇＇＇,4＇＇＇＇＇-o][1,2,9,10]-tetraazacyclohexadecine,were investigated to verify its capacity as high energy density material（HEDM）. The infrared spectrum was also predicted. The heat of formation（HOF） was calculated using designed isodesmic reaction. The calculation on the bond dissociation energies（BDEs） was done and the pyrolysis mechanism of the compound was studied. The result shows that the N3–O1 bond in the ring may be the weakest one and the ring cleavage is possible to happen in thermal decomposition. The condensed phase HOF and the crystal density were also calculated for the title compound. The detonation data show that it can be considered as a potential HEDM. These results would provide basic information for the molecular design of novel high energy materials.
基金Supported by the National Sci-Tech Support Plan(2015BAD21B05)China Scholarship Council(201408320127)
文摘Amorphous carbon materials play a vital role in adsorbed natural gas(ANG) storage. One of the key issues in the more prevalent use of ANG is the limited adsorption capacity, which is primarily determined by the porosity and surface characteristics of porous materials. To identify suitable adsorbents, we need a reliable computational tool for pore characterization and, subsequently, quantitative prediction of the adsorption behavior. Within the framework of adsorption integral equation(AIE), the pore-size distribution(PSD) is sensitive to the adopted theoretical models and numerical algorithms through isotherm fitting. In recent years, the classical density functional theory(DFT) has emerged as a common choice to describe adsorption isotherms for AIE kernel construction. However,rarely considered is the accuracy of the mean-field approximation(MFA) commonly used in commercial software. In this work, we calibrate four versions of DFT methods with grand canonical Monte Carlo(GCMC) molecular simulation for the adsorption of CH_4 and CO_2 gas in slit pores at 298 K with the pore width varying from 0.65 to 5.00 nm and pressure from 0.2 to 2.0 MPa. It is found that a weighted-density approximation proposed by Yu(WDA-Yu) is more accurate than MFA and other non-local DFT methods. In combination with the trapezoid discretization of AIE, the WDA-Yu method provides a faithful representation of experimental data, with the accuracy and stability improved by 90.0% and 91.2%, respectively, in comparison with the corresponding results from MFA for fitting CO_2 isotherms. In particular, those distributions in the feature pore width range(FPWR)are proved more representative for the pore-size analysis. The new theoretical procedure for pore characterization has also been tested with the methane adsorption capacity in seven activated carbon samples.
基金Projects(2006DFA41090,2007DFA40680) supported by the International Cooperation Project on Traditional Chinese Medicines of Ministry of Science and Technology of ChinaProject(20475066) supported by the National Natural Science Foundation of China
文摘To further test whether polynitriprismanes are capable of being potential high energy density materials （HEDMs）, extensive theoretical calculations were carried out to investigate on a series of polynitrotriprismanes （PNNPs）： C6H6-.（NO2）. （n=1-6） Heats of formation （HOFs）, strain energies （SE）, and disproportionation energy （DE） were obtained using B3LYP/6-311＋G（2df, 2p）//B3LYP/6-31G＊ method by designing different isodesmic reactions, respectively. Detonation properties of PNNPs were obtained by the well-known KAMLET-JACOBS equations, using the predicted densities （p） obtained by Monte Carlo method and HOFs. It is found that they increase as the number of nitro groups n varies from 1 to 6, and PNNPs with n〉4 have excellent detonation properties The relative stability and the pyrolysis mechanism of PNNPs were evaluated by the calculated bond dissociation energy （BDE）. The comparison of BDE suggests that rupturing the C--C bond is the trigger for thermolysis of PNNPs. The computed BDE for cleavage of C--C bond （88.5 kJ/mol） further demonstrates that only the hexa-nitrotriprismane can be considered to be the target of HEDMs.
基金National Natural Science Foundation of China(No.11805157)Sichuan Provincial Department of Science and Technology Application Fundamental Research,China(No.2017JY0146)+1 种基金China West Normal University Scientific Research Innovation Team Project(No.CXTD2016-2)China West Normal University Talent Research Fund Project(No.CXTD2017-10)。
文摘The cyclo-N_(6)anion is a total nitrogen unit with higher nitrogen content than cyclo-N^(-)_(5).However,the low decomposition barrier of cyclo-N_(6)anions hinders its application as a high energy density material(HEDM).Using first-principles calculations,we reveal that the covalent components that enhance the interaction between the cyclo-N_(6)anion and the cation can effectively improve the stability of cyclo-N_(6)anions.The actinide metals(Th,Pa,U)are selected as suitable cations.Further electronic structure analysis showed that the charge transfer from the actinide metal to cyclo-N_(6)anions resulted in a strong covalent bond,which promoted the stability of the cyclo-N_(6)anion in the Th(N_(6)),Pa(N_(6)),and U(N_(6))structure.This discovery is helpful for the rational design and synthesis of new HEDMs.
基金financial support from the National Key R&D Program of China(Grant No.2016YFA0300404)the National Natural Science Foundation of China(Grant Nos.11974162,and 11834006)+1 种基金the Fundamental Research Funds for the Central Universitiesfinancial support from the Project funded by China Postdoctoral Science Foundation(Grant No.2019M651767)。
文摘The search for high energy density materials(HEDMs)in polymeric nitrogen compounds has gained considerable attention.Previous theoretical predictions and experiments have revealed that metal ions can be used to stabilize the pentazolate(N-5)anion.In this work,by employing a machine learning-accelerated crystal structure searching method and first-principles calculations,we found that the new pentazolate salts,CaN(10)and BaN(10),are energetically favorable at high pressures.Phonon dispersion calculations reveal that they are quenchable at ambient pressure.Ab initio molecular dynamics simulations verify their dynamic stability at finite temperature.Bader charge and electron localization function illustrates that alkaline earth atoms serve as electron donors,contributing to the stability of N5 rings.Bonding calculations reveal covalent bonds between nitrogen atoms and weak interactions between N5 rings.Similar to other pentazolate salts,these polymeric nitrides have high energy densities of approximately 2.35 kJ/g for CaN(10)and 1.32 kJ/g for BaN(10).The predictions of CaN(10)and BaN(10)structures indicate that these salts are potential candidates for green nitrogen-rich HEDMs.
基金the of Tangshan Normal University(2021B37and 2021B32)the School Fund of Shanxi Institute of Technology(2019004)the Fund of Shanxi Provincial Education Department(2019L0986)。
文摘The geometric and electronic structures of the derivatives of 4-nitro-5-(5-nitroimino-1,2,4-triazol-3-yl)-2H-1,2,3-triazolate(named A~J)are explored employing density functional theory(DFT)calculations at the B3LYP/6-311G^(**)level of theory.Based on the optimized molecular structures,the heats of formation(HOF)are obtained,and the electronic properties,density and molecular sensitivity by characteristic heights(H_(50))are discussed.Besides,the detonation performances(detonation velocity,detonation pressure)are estimated via Kamlet-Jacobs(K-J)formula.Compounds B(H50=29.4 cm,ρ=1.91 g/cm^(3),Q=1563.04 cal/g,P=36.05 GPa,D=8.95 km/s)and H(H_(50)=31.9 cm,ρ=1.80 g/cm^(3),Q=1610.09 cal/g,P=37.31 GPa,D=9.12 km/s)have positive HOFs and remarkable insensitivity and good detonation performance,strongly suggesting them as the acceptable new-type explosive.The initiating power surpasses conventional primary explosives,such as HMX.The outstanding detonation power of compounds B and H contributes to its future prospects as a promising green primary explosive.
基金J.S.gratefully acknowledges the financial support from the National Natural Science Foundation of China(12125404,11974162,11834006)the Fundamental Research Funds for the Central Universities.K.X.acknowledges the National Natural Science Foundation of China under 12004185+2 种基金the Natural Science Foundation of the Jiangsu Higher Education Institutions of China under 20KJB140016the Scientific Research Start-up Funds of Nanjing Forestry University(163101110)the financial support from the Project funded by China Postdoctoral Science Foundation(2019M651767).
文摘In recent decades,pentazolate salts have gained considerable attention as high energy density materials(HEDMs).Using the machine-learning accelerated structure searching method,we predicted four pentazolate salts stabilized with tetravalent metals(Ti-N and Zr-N).Specifically,the ground state MN_(20)(M=Ti,Zr)adopts the space-group P 4/mcc under ambient conditions,transforming into the I-4 phase at higher pressure.Moreover,the I-4-MN_(20)becomes energetically stable at moderate pressure(46.8 GPa for TiN_(20),38.7 GPa for ZrN_(20)).Anharmonic phonon spectrum calculations demonstrate the dynamic stabilities of these MN_(20)phases.Among them,the P 4/mcc phase can be quenched to 0 GPa.Further ab-initio molecular dynamic simulations suggest that the N_(5)rings within these MN_(20)systems can still maintain integrity at finite temperatures.Calculations of the projected crystal orbital Hamilton population and reduced density gradient revealed their covalent and noncovalent interactions,respectively.The aromaticity of the N_(5)ring was investigated by molecular orbital theory.Finally,we predicted that these MN_(20)compounds have very high energy densities and exhibit good detonation velocities and pressures,compared to the HMX explosive.These calculations enrich the family of pentazolate compounds and may also guide future experiments.
基金Projects supported by the National Natural Science Foundation of China(Grant Nos.11972138,11672094).
文摘This paper presents a numerical study of the hydroelastic coupling during the free-surface water entry of deformable spheres of different material densities.The focus is on the hydrodynamic forces,the stress loads,the sphere deformations,the wetted areas of the sphere and the cavity dynamics,including the impacting of the elastic spheres and the hydroelastic coupled behaviors in the free surface flows.It is shown that the elastic wave propagation in the sphere scales with the sphere density.For elastic spheres immersed in the water,the variation of the sphere deformations and its energy transformation mechanism are discussed.From the contact point positions of the cavity,it can be seen that the wetted area of the sphere is closely related with the sphere deformation.The first deformation cycle is a turning point in the relation between the wetted area and the sphere density.Based on the map of m*−ηsummarized in this work,the influence of the sphere deformation on the shape of the cavity can be roughly predicted from the material properties and the impact conditions.
文摘Ninety-one nitro and hydroxyl derivatives of benzene were studied at the B3LYP/6-31G＊ level of density functional theory. Detonation properties were calculated using the Kamlet-Jacobs equation. Three candidates （pentanitrophenol, pentanitrobenzene, and hexanitrobenzene） were recommended as potential high energy density compounds for their perfect detonation performances and reasonable stability. The pyrolysis mechanism was studied by analyzing the bond dissociation energy （BDE） and the activation energy （Ea） of hydrogen transfer （H--T） reaction for those with adjacent nitro and hydroxyl groups. The results show that Ea is much lower than BDEs of all bonds, so when there are adjacent nitro and hydroxyl groups in a molecule, the stability of the compound will decrease and the pyrolysis will be initiated by the H--T process. Otherwise, the pyrolysis will start from the breaking of the weakest C--NO2 bond, and only under such condition, the Mulliken population or BDE of the C--NO2 bond can be used to assess the relative stability of the compound.
文摘Density functional theory (DFT) method has been employed to study the effect of nitroamino group as a substituent in cyclopentane and cyclohexane, which usually construct the polycyclic or caged nitra-mines. Molecular structures were investigated at the B3LYP/6-31G** level, and isodesmic reactions were designed for calculating the group interactions. The results show that the group interactions ac-cord with the group additivity, increasing with the increasing number of nitroamino groups. The dis-tance between substituents influences the interactions. Detonation performances were evaluated by the Kamlet-Jacobs equations based on the predicted densities and heats of formation, while thermal stability and pyrolysis mechanism were studied by the computations of bond dissociation energy (BDE). It is found that the contributions of nitroamino groups to the detonation heat, detonation velocity, detonation pressure, and stability all deviate from the group additivity. Only 3a, 3b, and 9a-9c may be novel potential candidates of high energy density materials (HEDMs) according to the quantitative cri-teria of HEDM (ρ ≈ 1.9 g/cm3, D ≈ 9.0 km/s, P ≈ 40.0 GPa). Stability decreases with the increasing number of N-NO2 groups, and homolysis of N-NO2 bond is the initial step in the thermolysis of the title com-pounds. Coupled with the demand of thermal stability (BDE > 20 kcal/mol), only 1,2,4-trinitrotriazacy-clohexane and 1,2,4,5-tetranitrotetraazacyclohexane are suggested as feasible energetic materials. These results may provide basic information for the molecular design of HEDMs.
