臺灣博碩士論文加值系統

本篇文章使用第一原理計算討論奈米碳捲的物理性質。比較兩種不同形式的奈米碳捲分別為扶手狀與鋸齒狀。其中討論的項目有鍵長，基態能量，電子結構和能隙。而奈米碳管是由一張單層的石墨烯所捲起來的。在最邊緣的碳原子則是和氫原子作鑑結，而碳與碳之間的鍵結則是在最邊緣的時候鍵結長度最小。扶手狀與鋸齒狀的最小小管徑分別是5.54Å和6.95Å。總基態能量與寬度有著強烈的關係，並且能量差主要由凡德瓦力在不同寬度下所造成。扶手狀是由它的寬度來決定其為金屬或半導體，而鋸齒狀則擁有反鐵磁的結構所以為半導體。並且其能隙會隨著寬度變大而呈現變小的趨勢。

The physical properties of carbon nanoscoll (CNS) were studied by using the first principles methods within the generalized gradient approximation. Two different kinds of chiral (armchair and zigzag) CNS s are considered and their properties were compared. Bond lengths, ground state energies, band structures, and band gaps are discussed. The CNS can be regarded as a rolled up single layer graphene. The atoms at the edge are saturated by hydrogen atoms and the C-C bond length near the edge is smaller. The minimum diameters of the armchair and zigzag CNSs are 5.54Å and 6.95Å, respectively. The total ground state energy is strongly dependent on the width. And the energy difference induced by this width dependence is mainly contributed by the van der Waals and the strain energy. Armchair CNSs are metallic or semiconductor depending on their widths. Zigzag CNSs with an antiferromagnetic arrangement belong to semiconductors. And the energy gap is decreased by the width increment.

Chapter 1. Introduction…………………………………1
Chapter 2. Theory and methods………………………4
Chapter 3. Geometric and formation energy……………5
Chapter 4. Electronic properties………………………9
Chapter 5. The charge distribution and energy gaps……11
Chapter 6. Density of states…………………………13
Chapter 7. Concluding remarks………………………14
Figures…………………………………………………17
References……………………………………………25

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