The structure properties of hexagonal graphite under high pressure and the study of CeAl2-nanoparticle by first principle calculations

• Main Authors: Chong-Ching Chou, 朱公勍
• Other Authors: Ming-Hsien Lee
• Format: Others
• Language: zh-TW
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/38870130891000660196

碩士 === 淡江大學 === 物理學系 === 87 === The structure of hexagonal graphite under high pressure has been a puzzle to experimentalists.This is because people represent different view-points from the results of the experiments of high-pressure X-ray and high-pressure Raman spectrum:Some people consider hexagonal graphite under high pressure should be the three dimensional structure of sp3 bonding by high-pressure X-ray and high-pressure Raman spectrum;however,other people believe it should be the layer structure of sp2 bonding by the same experimental devices. To figure out this problem,I use the first principle calculation of CASTEP(Cambridge Serial Total Energy Package),analysis of charge density and simulative analysis of X-ray.Finally we think that hexagonal graphite under high pressure should be the layer structure of sp2 bonding. Besides,we design serius of calculations about carbon and silicon ,then use our developmental program of LCAO(Linear Combination of Atomic Orbital) &PDOS(Partial Density Of State)to rejudge that why the layer structure of silicon doesn't exist in the nature environment . At the end,I use the LCAO&PDOS pattern to explore the valence charge change of Ce of CeAl2-bulk and CeAl2-nanoparticle from the observation in the experiment. We think that the change in the lattice constant of CeAl2-bulk is enough to influence the valence charge change of Ce of CeAl2-nanoparticle.