arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0803.0560cond-mat.mtrl-sci
收藏

碳富勒烯中中性和带电激发的第一性原理多体理论

Neutral and charged excitations in carbon fullerenes from first-principles many-body theories

Murilo L. Tiago, P. R. C. Kent, Randolph Q. Hood, Fernando A. Reboredo

摘要:

通过对碳富勒烯C_20、C_24、C_50、C_60、C_70和C_80的低能激发态与实验的比较,考察了第一性原理多体理论在纳米尺度下的准确性。通过GW-Bethe-Salpeter方程(GW-BSE)和扩散量子蒙特卡罗(QMC)方法计算属性。我们批判性地比较这些理论,并评估其准确性对现有的光吸收和光电子能谱学数据。第一电离势是一贯良好的再现,是相似的所有富勒烯和方法研究。电子亲合势和第一三重态激发能表现出实质性的方法和几何形状的依赖性。这些结果确立了多体理论作为密度泛函理论在描述受限碳纳米结构的电子性质方面的可行替代方案的有效性。我们发现富勒烯的能隙和稳定性之间存在着相关性。我们还发现,富勒烯的电子亲和势是非常高的和尺寸无关的,这解释了它们倾向于形成化合物与电子供体阳离子。

英文摘要:

We investigate the accuracy of first-principles many-body theories at the nanoscale by comparing the low energy excitations of the carbon fullerenes C_20, C_24, C_50, C_60, C_70, and C_80 with experiment. Properties are calculated via the GW-Bethe-Salpeter Equation (GW-BSE) and diffusion Quantum Monte Carlo (QMC) methods. We critically compare these theories and assess their accuracy against available photoabsorption and photoelectron spectroscopy data. The first ionization potentials are consistently well reproduced and are similar for all the fullerenes and methods studied. The electron affinities and first triplet excitation energies show substantial method and geometry dependence. These results establish the validity of many-body theories as viable alternative to density-functional theory in describing electronic properties of confined carbon nanostructures. We find a correlation between energy gap and stability of fullerenes. We also find that the electron affinity of fullerenes is very high and size-independent, which explains their tendency to form compounds with electron-donor cations.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑