本文關(guān)鍵詞：晶格反演修正型嵌入原子勢(shì)函數(shù)理論及應(yīng)用研究　出處：《華中科技大學(xué)》2015年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 分子動(dòng)力學(xué) 勢(shì)函數(shù) 多體勢(shì) 修正型嵌入原子勢(shì) 第二近鄰修正型嵌入原子勢(shì) 品格反演法 多體屏蔽函數(shù) 勢(shì)參數(shù)優(yōu)化 過(guò)渡族bcc金屬

【摘要】：隨著計(jì)算機(jī)軟硬件性能的提升和互聯(lián)網(wǎng)技術(shù)的發(fā)展,計(jì)算材料學(xué)在新材料研發(fā)中起到了越來(lái)越重要的作用。作為其中的一個(gè)重要分支,分子動(dòng)力學(xué)在進(jìn)行原子尺度上模擬中得到了廣泛的應(yīng)用。盡管分子動(dòng)力學(xué)方法涉及到眾多的技術(shù),但勢(shì)函數(shù)因著其對(duì)計(jì)算結(jié)果可靠性的決定性作用而成為最受人們關(guān)注的一個(gè),幾乎伴隨著分子動(dòng)力學(xué)方法的整個(gè)發(fā)展歷程。時(shí)至今日,人們?nèi)栽趪L試開發(fā)出具有更高精度、更高效率和更高擴(kuò)展性的勢(shì)函數(shù)。本文的主要研究工作也是圍繞這一主題展開,特別是引入了晶格反演法作為勢(shì)函數(shù)開發(fā)的工具。下面是對(duì)本文主要工作的簡(jiǎn)單總結(jié)。 首先,使用晶格反演法,以第一性原理計(jì)算的結(jié)合能曲線為基礎(chǔ),發(fā)展了適用于Pd-Au間的反演對(duì)勢(shì)。然后以該對(duì)勢(shì)為基礎(chǔ),研究了Pd-Au合金納米顆粒熔化行為的尺寸效應(yīng)及表面原子偏聚現(xiàn)象。 其次,在修正型嵌入原子勢(shì)(MEAM)的基礎(chǔ)上,通過(guò)移除其中所使用的復(fù)雜的多體屏蔽函數(shù),并使用晶格反演法考慮更多近鄰原了對(duì)對(duì)勢(shì)和電子密度的貢獻(xiàn),提出了一種新的勢(shì)函數(shù)模型,即晶格反演修正型嵌入原子勢(shì)(LI-MEAM)。相比于之前的MEAM勢(shì)函數(shù),LI-MEAM的模型更簡(jiǎn)單,勢(shì)參數(shù)更少,物理意義更明確,同時(shí)精度也有提高。除此之外,在納米顆粒的應(yīng)用中,LI-MEAM表現(xiàn)出更好的穩(wěn)定性。 第三,使用粒子群優(yōu)化算法優(yōu)化了Fe在LI-MEAM下的勢(shì)參數(shù)。然后使用優(yōu)化的勢(shì)參數(shù),計(jì)算了Fe的各種物理性質(zhì),并將這些結(jié)果與實(shí)驗(yàn)值及其他勢(shì)函數(shù)的計(jì)算結(jié)果進(jìn)行比較。對(duì)比結(jié)果顯示,作為一種簡(jiǎn)化的MEAM勢(shì)函數(shù),LI-MEAM仍然具有略高于第二近鄰的修正型嵌入原子勢(shì)(2NN MEAM)的精度。另外還使用LI-MEAM研究了bcc-Fe球形納米顆粒熔化行為的尺寸效應(yīng)及熔化機(jī)理。 最后,使用粒子群優(yōu)化算法優(yōu)化了所有過(guò)渡族bcc體系(Fe、Cr、Mo、V、Nb及Ta)在LI-MEAM下的勢(shì)參數(shù)。然后使用這些優(yōu)化的勢(shì)參數(shù),計(jì)算了各個(gè)過(guò)渡族bcc體系的多種物理性質(zhì),并將這些結(jié)果與實(shí)驗(yàn)值及2NN MEAM的計(jì)算結(jié)果進(jìn)行比較。結(jié)果顯示,在LI-MEAM勢(shì)函數(shù)下使用這些參數(shù)計(jì)算出的各體系的物理性質(zhì)具有很高的精度。
[Abstract]:With the improvement of computer hardware and software performance and the development of Internet technology, computational materials science plays an increasingly important role in the research and development of new materials. Molecular dynamics has been widely used in atomic scale simulations, although molecular dynamics methods involve many techniques. However, the potential function has become the most concerned because of its decisive effect on the reliability of the calculation results, and almost accompanied by the entire development of molecular dynamics methods. People are still trying to develop potential functions with higher accuracy, higher efficiency and higher expansibility. In particular, the lattice inversion method is introduced as a tool for the development of potential functions. The following is a brief summary of the main work in this paper. First, using lattice inversion method, based on the binding energy curve calculated by first principle, the inversion potential suitable for Pd-Au is developed, and then it is based on this pair potential. The size effect of the melting behavior of Pd-Au alloy nanoparticles and the phenomenon of surface atomic segregation were studied. Secondly, based on the modified embedded atom potential (MEAM), the complex multibody shielding function is removed. The lattice inversion method is used to consider the contribution of more nearest neighbors to the potential and electron density, and a new potential function model is proposed. That is, the lattice inversion modified embedded atom potential LI-MEAM is simpler than the previous MEAM potential function and has fewer potential parameters and clearer physical meaning. In addition, LI-MEAM shows better stability in the application of nanoparticles. Thirdly, particle swarm optimization algorithm is used to optimize the potential parameters of Fe under LI-MEAM, and then the physical properties of Fe are calculated by using the optimized potential parameters. These results are compared with experimental values and other potential functions. The results show that these results are a simplified MEAM potential function. LI-MEAM still has a modified embedded atomic potential slightly higher than the second nearest neighbor. LI-MEAM was also used to study the size effect and melting mechanism of bcc-Fe spherical nanoparticles. Finally, the particle swarm optimization algorithm is used to optimize all transition bcc systems. The potential parameters of NB and Ta) under LI-MEAM are used to calculate the physical properties of each transition family bcc system. These results are compared with experimental values and 2NN MEAM results. The physical properties of each system calculated by using these parameters under the LI-MEAM potential function have high accuracy.
【學(xué)位授予單位】：華中科技大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類號(hào)】：TB383.1

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