【摘要】：目前,多元金屬團(tuán)簇成為材料科學(xué)領(lǐng)域比較熱門的研究課題之一,受到廣泛的關(guān)注。由于團(tuán)簇勢能曲面上局部極小值的數(shù)量非常龐大,且構(gòu)型空間隨著體系尺寸呈指數(shù)性增長,因此多元團(tuán)簇的結(jié)構(gòu)優(yōu)化是相當(dāng)困難的。本論文的主要工作是多元金屬團(tuán)簇的結(jié)構(gòu)優(yōu)化。除此之外,還提出了一種AIOA算法的改進(jìn)算法。以全局優(yōu)化算法作為理論分析的方法,探究多元合金團(tuán)簇在結(jié)構(gòu)和性質(zhì)上存在的規(guī)律。論文的主要內(nèi)容概括如下:1.采用多體勢Gupta函數(shù)描述團(tuán)簇金屬原子間作用。使用AIOA算法優(yōu)化了38原子Au-Pd-Pt的最穩(wěn)定結(jié)構(gòu)。結(jié)果顯示團(tuán)簇的結(jié)構(gòu)類型包括Marks十面體、不完整的Mackay二十面體、完整的截角八面體、密堆積面心立方以及無定型結(jié)構(gòu)。序列參數(shù)表明Au、Pd、Pt原子具有分層現(xiàn)象。Au原子分散于團(tuán)簇內(nèi)殼,Pt原子在團(tuán)簇表面生長,而Pd原子與Au原子混融。此外,還通過計(jì)算團(tuán)簇的勢能量二階有限差分值Δ2E和ΔGupta值,比較了近鄰團(tuán)簇之間的相對穩(wěn)定性。2.使用AIOA算法搜索原子達(dá)75的M-Pd-Pt(M=Ag、Au)團(tuán)簇穩(wěn)定結(jié)構(gòu)。討論不同類型原子摻雜導(dǎo)致的Pd-Pt結(jié)構(gòu)變化。13原子M-Pd-Pt(M=Ag、Au)團(tuán)簇中存在二十面體和非二十面體兩種構(gòu)型,并且Au-Pd-Pt中非二十面體數(shù)量要比Ag-Pd-Pt中非二十面體數(shù)量多�？疾炝瞬煌愋徒饘僭拥纳L模式,發(fā)現(xiàn)在Ag-Pd-Pt和Au-Pd-Pt中Pd和Pt原子在團(tuán)簇結(jié)構(gòu)中的分布比較相似,但是Au原子比Ag原子更容易聚集生長。最后通過Δ2E值比較了相鄰團(tuán)簇之間的穩(wěn)定性。3.提出了一種改進(jìn)的AIOA算法,稱之為AIOA-BDLS-ILS算法。以二元LJ函數(shù)模型測試該算法的效率,發(fā)現(xiàn)比BDLS-ILS算法更高效。使用該算法優(yōu)化34原子Pd-Pt團(tuán)簇時(shí),找到了12個(gè)能量更低的結(jié)構(gòu)。此外,還優(yōu)化了50及79原子。序列參數(shù)顯示Pd和Pt原子有明顯的分層現(xiàn)象。
[Abstract]:At present, multi-metal clusters have become one of the hot research topics in the field of material science, and have received extensive attention. Because the number of local minimums on cluster potential energy surfaces is very large, and the configuration space increases with the size of the system, it is very difficult to optimize the structure of multivariate clusters. The main work of this paper is the structural optimization of multicomponent metal clusters. In addition, an improved algorithm of AIOA algorithm is proposed. The global optimization algorithm is used as the theoretical analysis method to explore the law of the structure and properties of multicomponent alloy clusters. The main contents of the paper are summarized as follows: 1. The multibody potential Gupta function is used to describe the interaction between cluster metal atoms. The most stable structure of 38 atom Au-Pd-Pt is optimized by AIOA algorithm. The results show that the structural types of clusters include Mark decahedral, incomplete Mackay icosahedral, complete truncated octahedral, dense stacked face centered cubic and amorphous structure. The sequence parameters show that Au,Pd,Pt atoms have delamination phenomenon. Au atoms are dispersed in the inner shell of clusters, Pt atoms grow on the surface of clusters, and Pd atoms are mixed with Au atoms. In addition, by calculating the second order finite difference values 螖 2E and 螖 Gupta of the potential energy of the cluster, the relative stability between the nearest neighbor clusters is compared. 2. The AIOA algorithm is used to search the stable structure of M-Pd-Pt (M 鈮，

本文編號：2476918