In this work we present the results of our study on the physical and mechanical properties of titanium in volume. The work consisted in determining its physical and mechanical properties under different crystallograph...In this work we present the results of our study on the physical and mechanical properties of titanium in volume. The work consisted in determining its physical and mechanical properties under different crystallographic structures (HCP, FCC, BCC and SC) using the Modified Embedded Atom Method (MEAM) and the MEAM potential of titanium. We used the LAMMPS calculation code, based on classical molecular dynamics, to determine the most stable structure of titanium, which is the hexagonal compact structure (HCP) with crystal parameters a = 2.952 Å and c = 4.821 Å and a cohesion energy of -4.87 eV. This structure is seconded by the cubic centred structure (BCC) with a lattice parameter a = 3.274 Å and a cohesive energy of -4.84 eV. It was shown that titanium can crystallise into a third structure which is the face-centred cubic (FCC) structure with a lattice parameter a = 4.143 Å and a cohesive energy of -4.82 eV. The results obtained in this study were compared with the theoretical results and showed considerable agreement.展开更多
In this work, we have studied the vacancy formation energy of TiN alloy of structure B2 of size 10 × 10 × 10 for nitrogen percentages of 45%, 50% and 55% under the influence of temperature at 1320 K, 1420 K ...In this work, we have studied the vacancy formation energy of TiN alloy of structure B2 of size 10 × 10 × 10 for nitrogen percentages of 45%, 50% and 55% under the influence of temperature at 1320 K, 1420 K and 1520 K using the Modified Embedded Atom Method MEAM under the calculation code LAMMPS version 2020. This study has enabled us to understand the behavior of the TiN alloy under different nitrogen percentages in terms of total energy, vacancy formation energy, crystalline parameter, occupancy rate and order parameter. For total energy, we have shown that as temperature increases, total energy decreases, making it easier to obtain TiN at higher temperatures;reaching the value of -7344.9169 eV for the 55% nitrogen structure for the temperature of 1420 K. For the energy of formation, we have shown that the compounds obtained at 1320 K and 1520 K have a more considerable energy of formation than that obtained at 1420 K. The study of fractions and the order parameter showed us that the structure of TiN with 55% nitrogen is less likely, as the composition obtained is at most 53.35%.展开更多
The modified embedded atom method(MEAM)with the universal form of embedding function and a modified energy term along with the pair potential has been employed to determine the potentials for alkali metals:Na,K,by fit...The modified embedded atom method(MEAM)with the universal form of embedding function and a modified energy term along with the pair potential has been employed to determine the potentials for alkali metals:Na,K,by fitting to the Cauchy pressure(C_(12)−C_(44))/2,shear constants Gv=(C_(11)−C_(12)+3C_(44))/5 and C_(44),the cohesive energy and the vacancy formation energy.The obtained potentials are used to calculate the phonon dispersions of these metals.Using these calculated phonons we evaluate the local density of states of neighbours of vacancy using Green’s function method.The local density of states of neighbours of vacancy has been used to calculate mean square displacements of these atoms and formation entropy of vacancy.The calculated mean square displacements of both 1st and 2nd neighbours of vacancy are found to be lower than that of host atom.The calculated phonon dispersions agree well with the experimental phonon dispersion curves and the calculated results of vacancy formation entropy compare well with the other available results.展开更多
To explore atomic-level phenomena in the Cu-Ni-Sn alloy,a second nearest-neighbor modified embedded-atom method(2NN MEAM)potential has been developed for the Cu-Ni-Sn system,building upon the work of other researchers...To explore atomic-level phenomena in the Cu-Ni-Sn alloy,a second nearest-neighbor modified embedded-atom method(2NN MEAM)potential has been developed for the Cu-Ni-Sn system,building upon the work of other researchers.This potential demonstrates remarkable accuracy in predicting the lattice constant,with a relative error of less than 0.5%when compared to density functional theory(DFT)results,and it achieves a 10%relative error in the enthalpy of formation compared to experimental data,marking substantial advancements over prior models.The bulk modulus is predicted with a relative error of 8%compared to DFT.Notably,the potential effectively simulates the processes of melting and solidification of Cu-15Ni-8Sn,with a simulated melting point that closely aligns with the experimental value,within a 7.5%margin.This serves as a foundation for establishing a 2NN MEAM potential for a flawless Cu-Ni-Sn system and its microalloying systems.展开更多
文摘In this work we present the results of our study on the physical and mechanical properties of titanium in volume. The work consisted in determining its physical and mechanical properties under different crystallographic structures (HCP, FCC, BCC and SC) using the Modified Embedded Atom Method (MEAM) and the MEAM potential of titanium. We used the LAMMPS calculation code, based on classical molecular dynamics, to determine the most stable structure of titanium, which is the hexagonal compact structure (HCP) with crystal parameters a = 2.952 Å and c = 4.821 Å and a cohesion energy of -4.87 eV. This structure is seconded by the cubic centred structure (BCC) with a lattice parameter a = 3.274 Å and a cohesive energy of -4.84 eV. It was shown that titanium can crystallise into a third structure which is the face-centred cubic (FCC) structure with a lattice parameter a = 4.143 Å and a cohesive energy of -4.82 eV. The results obtained in this study were compared with the theoretical results and showed considerable agreement.
文摘In this work, we have studied the vacancy formation energy of TiN alloy of structure B2 of size 10 × 10 × 10 for nitrogen percentages of 45%, 50% and 55% under the influence of temperature at 1320 K, 1420 K and 1520 K using the Modified Embedded Atom Method MEAM under the calculation code LAMMPS version 2020. This study has enabled us to understand the behavior of the TiN alloy under different nitrogen percentages in terms of total energy, vacancy formation energy, crystalline parameter, occupancy rate and order parameter. For total energy, we have shown that as temperature increases, total energy decreases, making it easier to obtain TiN at higher temperatures;reaching the value of -7344.9169 eV for the 55% nitrogen structure for the temperature of 1420 K. For the energy of formation, we have shown that the compounds obtained at 1320 K and 1520 K have a more considerable energy of formation than that obtained at 1420 K. The study of fractions and the order parameter showed us that the structure of TiN with 55% nitrogen is less likely, as the composition obtained is at most 53.35%.
文摘[目的]植物体内蛋白酶抑制剂(Protease inhibitors,PIs)主要参与防御病原物和植食性害虫为害以及应对非生物胁迫。但关于辣椒受MEAM1烟粉虱为害后,PIs的诱导和功能研究鲜见,相关研究有待深入。[方法]本研究拟通过对辣椒PIs的cDNA序列进行聚类分析,并运用qRT-PCR比较MEAM1烟粉虱(Middle East-Asia Minor 1)取食辣椒与对照未受害辣椒叶片PIs生物合成基因表达量差异,探究PIs在辣椒防御MEAM1为害过程中发挥作用。[结果]研究结果显示,辣椒体内的PI-Ⅱ类型基因进化保守,MEAM1烟粉虱取食可以诱导辣椒PIs生物合成相关基因表达显著上调。[结论]推测辣椒PIs在辣椒防御MEAM1烟粉虱为害过程中发挥重要作用。
文摘The modified embedded atom method(MEAM)with the universal form of embedding function and a modified energy term along with the pair potential has been employed to determine the potentials for alkali metals:Na,K,by fitting to the Cauchy pressure(C_(12)−C_(44))/2,shear constants Gv=(C_(11)−C_(12)+3C_(44))/5 and C_(44),the cohesive energy and the vacancy formation energy.The obtained potentials are used to calculate the phonon dispersions of these metals.Using these calculated phonons we evaluate the local density of states of neighbours of vacancy using Green’s function method.The local density of states of neighbours of vacancy has been used to calculate mean square displacements of these atoms and formation entropy of vacancy.The calculated mean square displacements of both 1st and 2nd neighbours of vacancy are found to be lower than that of host atom.The calculated phonon dispersions agree well with the experimental phonon dispersion curves and the calculated results of vacancy formation entropy compare well with the other available results.
基金sponsored by the Science and Technology Foundation of Guizhou Provincial Education Department(No.QJJ[2024]60)Guizhou Provincial Basic Research Program(Natural Science)(No.QKHJC[2024]Youth 214)+1 种基金Science and Technology Foundation of Guizhou Minzu University(No.GZMUZK[2024]QD21)Research Projects of Anshun University(No.asxybsjj202413).
文摘To explore atomic-level phenomena in the Cu-Ni-Sn alloy,a second nearest-neighbor modified embedded-atom method(2NN MEAM)potential has been developed for the Cu-Ni-Sn system,building upon the work of other researchers.This potential demonstrates remarkable accuracy in predicting the lattice constant,with a relative error of less than 0.5%when compared to density functional theory(DFT)results,and it achieves a 10%relative error in the enthalpy of formation compared to experimental data,marking substantial advancements over prior models.The bulk modulus is predicted with a relative error of 8%compared to DFT.Notably,the potential effectively simulates the processes of melting and solidification of Cu-15Ni-8Sn,with a simulated melting point that closely aligns with the experimental value,within a 7.5%margin.This serves as a foundation for establishing a 2NN MEAM potential for a flawless Cu-Ni-Sn system and its microalloying systems.
