以分子動力學方式研究分子接面的熱傳導性質

我們研究分子接面的熱傳導性質，奈米尺度下的聲子傳輸，在德拜溫度以上的熱導與溫度成正比，而在德拜溫度以下熱導將與溫度的三次方成正比。藉由聲子的Laudauer- Buttier公式，最初此公式一般用於電子的彈道傳輸，所以我們預估奈米接面的熱導，在德拜溫度以上與溫度成正比，而在德拜溫度以下將與溫度成三次方的關係。　　熱導與溫度呈現三次方的關係完全不同於巨觀的系統，巨觀的系統下熱導是與溫度成線性關係。然而，熱導與溫度呈現三次方的關係尚未有實驗可以證實。　　在此研究中，我們從第一原理的方法來探討分子接面的熱傳導性質，結合密度泛函理論（Density Functional theory）和分子動力學（Molecular Dynamics）模擬整個系統。這種結合的方法讓我們可以確實地在原子尺度下從第一原理出發，並更進一步解釋基本的熱傳導的性質。

關鍵字

熱導；接面；分子動力學；密度泛函理論；第一原理；熱導率

並列摘要

The thermal conductance in nanoscale junctions is proportional to T3 due to the “ballistic” phonon transport. T3-dependent thermal conductance in nanojunctions is predicted by a phonon-version Laudauer-Buttier’s formula, which is similar its original form typically applied to the electron transport in ballistic regime. The T3 thermal conductance is quite different from that in the bulk system, where the thermal conductance is linearly proportional to temperature T. However, the T3-dependent thermal conductance has not yet been confirmed by experiments. In this research, we investigate the thermal conductance for molecular junctions from first-principles in an approach which combines density functional theory (DFT) and molecular dynamic (MD) simulations. This approach allows us to further elucidate the fundamental thermal transport properties at truly atomic level from first-principles.

並列關鍵字

Thermal conductance ； junction ； molecular dynamics ； Density Functional theory ； first principles ； Thermal conductivity

參考文獻

1. Zhixin Guo, Dier Zhang, and Xin-Gao Gong, Thermal conductivity of grapheme nanoribbons. Appl. Phys. Lett. 95, 163103(2009)

2. Nuo Yang, Gang Zhang, and Baowen Li, Ultralow Thermal Conductivity of Isotope-Doped Silicon Nanowires. Nano Lett., 8 (1), pp 276–280(2008)

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以分子動力學方式研究分子接面的熱傳導性質

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