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A Density Functional Theory Study for Wn C0,± (n=1-6) Clusters

Author: KangZhangLi
Tutor: ZhangXiuRong
School: Jiangsu University of Science and Technology
Course: Physical Electronics
Keywords: Density functional theory (DFT) WnC0, ± n = 1-6 Clusters Stable structure Electronic Properties Magnetic IR spectra Polarizability
CLC: O641.1
Type: Master's thesis
Year: 2011
Downloads: 8
Quote: 0
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Abstract


Clusters is one of the basic structural unit of the nano-structure of the material, the nature of the nano-materials can be provided by changing the cluster size, structure, composition and design. Therefore, clusters ground state structure, stability and electronic properties of the theory is an important issue in the design of the new material microstructure, one of major significance for the design new materials with specific performance. In this paper, density functional theory B3LYP method LANL2DZ basis set level of the W n C 0 ± (n = 1-6) clusters have been studied, its content and the main results are as follows: (1) First the W n C 0 ± (n = 1-6) clusters variety of possible configurations comprehensive The geometry optimization has been the W n 0, ± (n = 1-6) ground state structure of clusters, found the same size neutral, anion and cation clusters ground state structure, and most of the structure of the ground state spin multiplicity lower, with pure Wn clusters with a lower spin multiplicity similar. When the W atoms n gt; stable configuration from a flat surface into the establishment of the structure, while the incorporation of C atoms tend to be the most stable surface. By the average binding energy and the energy of second-order differential analysis showed that the incorporation of C atoms enhance the stability of the Wn clusters, when n gt; 1, the same size clusters strongest cation stability of clusters and neutral clusters weakest. W 3 C the highest stability of clusters can be regarded as W n C 0, ± (n = 1 to 6) Clusters primitive; (2) In the The get the W n C 0 ± (n = 1-6) on the basis of the cluster structure of the ground state, we used DFT hybrid density functional B3LYP method of the W n, C 0, ± (n = 1-6) clusters the physical and chemical properties of the ground state structure depth analysis by the natural bond orbital ( NBO) analysis the W n C 0, ± (n = 1-6) Clusters electronic distribution and WC between interactions with pure tungsten clusters the pros and cons of electronic capabilities than the comparison; magnetic aspects revealed by electron spin density maps and the frontier molecular orbital energy level diagram the W 2 C 0 ± and W < sub> 4 C 0, ± clusters magnetic sources; analysis the W n C 0 ± (n = 1 -6) clusters IR spectra characteristic frequency of the vibration mode, an explanation is given, and the associated red shift and blue shift; polarizability analysis shows clusters of external electric field response. In summary, this thesis is the first time on W n C 0 ± (n = 1-6) the structure and physical and chemical properties of clusters systems theory The research can provide a theoretical basis for the understanding of the tungsten carbide-rich tungsten case has certain theoretical significance, but also looking for new functional materials.

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CLC: > Mathematical sciences and chemical > Chemistry > Physical Chemistry ( theoretical chemistry ),chemical physics > Structural Chemistry > Chemical bond theory
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