Theory And Applications Of Lattice Inversion Modified Embedded Atom Method

With the improvement of computer hardware and software and the development of internet, computational materials science is playing a more and more important role in de-veloping new materials. As one of the various methods, molecular dynamics (MD) has won a variety of applications in microscale simulations. Although there are many techniques involving in MD, the interatomic potential has drawn the most attention of researchers for the decisive role in determining the reliability of the calculated results. Hence, it almost has accompanied the whole development of MD. Even up to nowadays, researchers are still trying to propose more accurate, more efficient, and more transferable interatomic potential. The main work in present dissertation is also centering on this topic. Specially, the lattice inversion method is introduced to assist the development of interatomic potential. The main content can be summarized as the following briefly.Firstly, we developed the interatomic potential between Pd and Au from first principle calculations by using lattice inversion method. With the developed potential, we researched both the size dependent effect of the melting point and the aggregation of specific atom in the surface of Pd-Au nanoparticles.Secondly, we proposed the lattice inversion modified embedded atom method (LI-MEAM) by removing the complex many-body screening function from modified embedded atom method (MEAM) potential and considering the contribution of more nearest neighbors on both the pair potential and the electron density using lattice inversion method. Compared with previous MEAM models, which includes both INN MEAM and2NN MEAM, LI-MEAM is with simpler model, less parameters, more clear physical meanings and higher accuracy and stability.Thirdly, we optimized the parameters of Fe for the newly developed LI-MEAM poten-tial using particles swarm optimization method. With the optimized potential parameters, we calculated the various physical properties of Fe, and compared the results with the avail- able experimental values and those calculated by other potentials. It is shown that as a simplified MEAM potential, LI-MEAM is with slightly higher accuracy than the second n-earest neighbor MEAM (2NN MEAM). Then we researched the size dependent of melting point and the melting mechanism of spherical bcc-Fe nanoparticles.Finally, we optimized the parameters for LI-MEAM potential of all the bcc transition metals using particle swarm optimization method. With the optimized potential parameters, we calculated the various physical properties of individual metals, and compared the results with the available experimental values and those calculated by other potential models. It shows that the calculated physical properties of involved metals by using the optimized parameters for LI-MEAM potential are with relatively high accuracy.