Using dispersion corrected density functional theory,we systematically examined the pressure effect on crystal structure,cell volume,and band gap of 1,3,5-triamino-2,4,6-trinitrobenzene(TATB)to understand its extraord...Using dispersion corrected density functional theory,we systematically examined the pressure effect on crystal structure,cell volume,and band gap of 1,3,5-triamino-2,4,6-trinitrobenzene(TATB)to understand its extraordinary chemical stability.Analysis of the Mulliken population and the electron density of states implied a possible charge transfer in TATB with increasing pressure.Raman and infrared spectra of TATB under hydrostatic pressure up to 30 GPa were simulated.The observed strong coupling between NH_2 groups and NO_(2) groups with increasing pressure,which is considered to have a tendency of energy transfer with these vibrational modes,was analyzed.The pressure-induced frequency shift of selected vibrational modes indicated minor changes of molecular conformation mainly by the rotation of NH_(2) groups.Compression behavior and spectroscopic property studies are expected to shed light on the physical and chemical properties of TATB on an atomistic scale.展开更多
Construction of suitable structural models in order to account for chemical short-range orders is the reason behind the difficult multi-scale computational simulation methods for solid solutions.Herein,using Ti-Mo all...Construction of suitable structural models in order to account for chemical short-range orders is the reason behind the difficult multi-scale computational simulation methods for solid solutions.Herein,using Ti-Mo alloys as representative,we used our cluster-plus-glue-atom model to address the chemical short-range orders for body-center cubic lattice.In accordance with the atomic interaction mode,an Mo solute atom would prefer 14 Ti solvent atoms as its nearest neighbors,forming a rhombic-dodecahedral cluster,and some next outer-shell Mo and Ti atoms would serve as the glue atoms,which is formulated as [Mo-Ti14](Mo,Ti)x.The number of glue atoms x corresponds to different spatial distribution of the clusters.One of the formula having good stability is [Mo-Ti14]Mo,i.e.,with one Mo as the glue atom.To verify its stability,mechanical properties and electronic density of state are obtained using the first-principles calculations and the Young’s modulus agrees with the experimental values.Also the formulated structural unit [Mo-Ti14]Mo is indeed verified by the cluster expansion method.This work then confirms the existence of simple structural unit covering the nearest neighbors and a few next outershell atoms for the Ti-Mo alloy of high structural stability.展开更多
基金Project supported by the Science Challenge Project of China(Grant No.TZ2016001)the National Natural Science Foundation of China(Grant Nos.11674046and 11372053)+2 种基金the Fundamental Research Funds for the Central Universities of China(Grant No.DUT17GF203)the Opening Project of State Key Laboratory of Explosion Science and Technology,Beijing Institute of Technology,China(Grant No.KFJJ16-01M)the Supercomputing Center of Dalian University of Technology,China
文摘Using dispersion corrected density functional theory,we systematically examined the pressure effect on crystal structure,cell volume,and band gap of 1,3,5-triamino-2,4,6-trinitrobenzene(TATB)to understand its extraordinary chemical stability.Analysis of the Mulliken population and the electron density of states implied a possible charge transfer in TATB with increasing pressure.Raman and infrared spectra of TATB under hydrostatic pressure up to 30 GPa were simulated.The observed strong coupling between NH_2 groups and NO_(2) groups with increasing pressure,which is considered to have a tendency of energy transfer with these vibrational modes,was analyzed.The pressure-induced frequency shift of selected vibrational modes indicated minor changes of molecular conformation mainly by the rotation of NH_(2) groups.Compression behavior and spectroscopic property studies are expected to shed light on the physical and chemical properties of TATB on an atomistic scale.
基金financially supported by the National Key Research and Development Program of China (Grant No. 2016YFB0101206)the Natural Science Foundation of China (Grant No. 11674045)。
文摘Construction of suitable structural models in order to account for chemical short-range orders is the reason behind the difficult multi-scale computational simulation methods for solid solutions.Herein,using Ti-Mo alloys as representative,we used our cluster-plus-glue-atom model to address the chemical short-range orders for body-center cubic lattice.In accordance with the atomic interaction mode,an Mo solute atom would prefer 14 Ti solvent atoms as its nearest neighbors,forming a rhombic-dodecahedral cluster,and some next outer-shell Mo and Ti atoms would serve as the glue atoms,which is formulated as [Mo-Ti14](Mo,Ti)x.The number of glue atoms x corresponds to different spatial distribution of the clusters.One of the formula having good stability is [Mo-Ti14]Mo,i.e.,with one Mo as the glue atom.To verify its stability,mechanical properties and electronic density of state are obtained using the first-principles calculations and the Young’s modulus agrees with the experimental values.Also the formulated structural unit [Mo-Ti14]Mo is indeed verified by the cluster expansion method.This work then confirms the existence of simple structural unit covering the nearest neighbors and a few next outershell atoms for the Ti-Mo alloy of high structural stability.
