CALYPSO晶体和团簇结构预测方法及应用

发布时间：2018-12-10 07:02

【摘要】：凝聚态物质结构的理论预测是一个具有挑战性的课题。课题组前期基于晶体对称性的分类检索思想，，结合粒子群多目标优化算法，引入结构表征的成键特征矩阵，提出并发展了卡里普索（CALYPSO）晶体结构预测方法，编制了具有自主知识产权的CALYPSO结构预测软件，现已成为结构预测领域的重要工具。本论文基于前期积累，发展了CALYPSO团簇结构预测方法，编制了相应的程序代码并集成于CALYPSO软件包中（见网址：http://www.calypso.cn），在此基础上，对锂的高压半导体相的结构和硼的团簇结构进行了系统的研究，获得了创新性结果： 1.综合考虑孤立体系的结构特点和复杂性，对CALYPSO方法中多种结构处理方法进行扩展，发展了CALYPSO团簇结构预测方法：引入点群对结构产生的限制，有效减少了探索空间的自由度，增加结构种群的多样性；引入成键特征矩阵，实现对团簇结构的唯一表征，用于排除相似结构，对搜索相空间进行有效划分；调整粒子群优化算法使其可以进行高效的团簇结构演化。系统的测试表明该方法可以进行高效可靠的团簇结构预测。 2.实验发现导电性极好的金属锂在高压下竟然失去了金属性，转变为半导体，这激发了人们对锂的高压半导体相结构的研究热潮。本文利用自主发展的CALYPSO晶体结构预测方法，提出在60万大气压下金属锂转变为一个晶体学单胞内包含40个原子的复杂底心正交结构（Aba2-40结构），该结构中由于芯电子的排斥作用，价电子被完全局域到晶格的间隙区域，失去了自由电子特性，金属锂变成了半导体。本文提出的半导体Aba2-40结构随后被实验证实。 3.富勒烯是纳米科学领域的重要结构单元，但至今未发现由非碳元素形成的富勒烯。本文利用自主发展的CALYPSO团簇结构预测方法，提出由38个硼原子组成的硼团簇具有类富勒烯结构，该结构由硼三角和硼六角组成，是一个六角空洞掺杂的二十面体。细致的电子结构计算表明该纯硼富勒烯结构具有较大的能隙、奇特的双重芳香性和满壳层的电子结构，能量上极为稳定。研究结果为实验合成出非碳富勒烯结构提供了重要的理论支撑。
[Abstract]:The theoretical prediction of condensed matter structure is a challenging subject. Based on the theory of crystal symmetry classification retrieval and particle swarm optimization (PSO), a new method of crystal structure prediction for Carripsos (CALYPSO) is proposed and developed by introducing the bond-forming characteristic matrix of structural representation. The CALYPSO structure prediction software with independent intellectual property rights has been developed and has become an important tool in the field of structure prediction. Based on the previous accumulation, this paper develops the CALYPSO cluster structure prediction method, compiles the corresponding program code and integrates it into the CALYPSO software package (see Web site: http://www.calypso.cn), on this basis, The structure of high voltage semiconductor phase of lithium and the cluster structure of boron are systematically studied. The innovative results are as follows: 1. Considering the structural characteristics and complexity of the isolated system, this paper extends several structural processing methods in the CALYPSO method and develops the CALYPSO cluster structure prediction method. The introduction of the point group limits the structure generation and effectively reduces the degree of freedom in the exploration space. Increasing the diversity of structural populations; The key feature matrix is introduced to realize the unique representation of the cluster structure, which is used to eliminate the similar structure and effectively partition the search phase space. The particle swarm optimization algorithm is adjusted to make the cluster structure evolve efficiently. The system tests show that this method can predict the cluster structure efficiently and reliably. 2. It is found that lithium, which has excellent conductivity, has lost its gold properties and changed into semiconductors at high voltage, which has stimulated the research on the phase structure of lithium in high-voltage semiconductors. In this paper, using the independently developed CALYPSO crystal structure prediction method, a complex bottom center orthogonal structure (Aba2-40) with 40 atoms in a crystallographic unit cell is proposed for the conversion of lithium metal into a crystallographic unit at 600000 atmospheres. Due to the repulsive effect of core electrons, the valence electrons are completely localized to the gap region of the lattice, and the free electron property is lost, and the lithium metal becomes a semiconductor. The semiconductor Aba2-40 structure proposed in this paper was subsequently verified by experiments. 3. Fullerene is an important structural unit in nanoscience, but no fullerenes formed by non-carbon elements have been found up to now. In this paper, using the independently developed CALYPSO cluster structure prediction method, it is proposed that the boron cluster composed of 38 boron atoms has fullerene-like structure, which is composed of boron triangle and boron hexagonal, and is an icosahedron doped with hexagonal cavity. Detailed electronic structure calculations show that the pure boron fullerene structure has a large energy gap, unique double aromaticity and full shell electronic structure, and the energy is extremely stable. The results provide important theoretical support for the experimental synthesis of non-carbon fullerenes.
【学位授予单位】：吉林大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：O469

【共引文献】