Nonadiabatic Excited-State Molecular Dynamics Modeling of Photoinduced Dynamics in Conjugated Molecules

Abstract Titanium alloys’ excellent mechanical and physical properties make it the most popular material widely used in aerospace, medical, nuclear and other significant industries. The study of titanium alloys mainly focused on the macroscopic mechanical mechanism. However, very few researches addressed the nanostructure of titanium alloys and its mechanical response in Nano-machining due to the difficulty to perform and characterize nano-machining experiment. Compared with nano-machining, nano-indentation is easier to characterize the microscopic plasticity of titanium alloys. This research presents a nano-indentation molecular dynamics model in titanium to address its microstructure alteration, plastic deformation and other mechanical response at the atomistic scale. Based on the molecular dynamics model, a complete nano-indentation cycle, including the loading and unloading stages, is performed by applying Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS). The plastic deformation mechanism of nano-indentation of titanium with a rigid diamond ball tip was studied under different indentation velocities. At the same time, the influence of different environment temperatures on the nano-plastic deformation of titanium is analyzed under the condition of constant indentation velocity. The simulation results show that the Young’s modulus of pure titanium calculated based on nano-indentation is about 110GPa, which is very close to the experimental results. The results also show that the mechanical behavior of titanium can be divided into three stages: elastic stage, yield stage and plastic stage during the nano-indentation process. In addition, indentation speed has influence on phase transitions and nucleation of dislocations in the range of 0.1–1.0 Å/ps.

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First-principles molecular dynamics modeling of UCl 3 in LiCl-KCl eutectic

Journal of Molecular Liquids ◽

10.1016/j.molliq.2017.03.099 ◽

2017 ◽

Vol 234 ◽

pp. 279-286 ◽

Cited By ~ 16

Author(s):

Jia Song ◽

Shuping Shi ◽

Xuejiao Li ◽

Liuming Yan

Keyword(s):

Molecular Dynamics ◽

First Principles ◽

Dynamics Modeling ◽

Molecular Dynamics Modeling ◽

First Principles Molecular Dynamics

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Molecular Dynamics Study of the Interaction of C-S-H and Chloride Ions

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.711.1061 ◽

2016 ◽

Vol 711 ◽

pp. 1061-1068

Author(s):

Yang Zhou ◽

Guo Dong Xu

Keyword(s):

Molecular Dynamics ◽

Calcium Silicate Hydrate ◽

Chloride Concentration ◽

Sorption Isotherms ◽

Hydration Product ◽

Chloride Ions ◽

Dynamics Modeling ◽

Solution Interface ◽

Molecular Dynamics Modeling ◽

Cement Based Materials

Molecular Dynamics was employed to investigate the interaction of calcium silicate hydrate (C-S-H), the primary hydration product of cement based materials, and chloride, causing severe durable problems of concrete. The 11Å tobermorite structure was chosen to describe the C-S-H structure and the CLAYFF force field was used. It is observed in the simulation that there are no bound chlorides at 303K, while a fraction of chlorides appear in the adsorption district of tobermorite/solution interface at 323K indicating the temperature increase can improve chloride sorption capacity of C-S-H. The formation of Ca-Cl cluster is found on the surface of tobermorite, which is assumed to promote the chloride sorption. The experimental results of sorption isotherms of C-S-H in CaCl2 and NaCl aqueous solutions with the same chloride concentration have proved this point. Other researchers have made the same conclusion by means of molecular dynamics modeling, NMR tests or zeta potential experiments.

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