We investigate the vibrational stability and the electronic structure of the proposed icosahedral fullerene-like cage structure of B80 [Szwacki, Sadrzadeh, and Yakobson, Phys. Rev. Lett. {\bf 98}, 166804 (2007)] by an all electron density functional theory using polarized Gaussian basis functions containing 41 basis functions per atom. The vibrational analysis of B$_{80}$ indicates that the icosahedral structure is vibrationally unstable with 7 imaginary frequencies. The equilibrium structure has $T_h$ symmetry and a {\em smaller} gap of 0.96 eV between the highest occupied and lowest unoccupied molecular orbital energy levels compared to the icosahedral structure. The static dipole polarizability of B$_{80}$ cage is 149 \AAA and the first ionization energy is 6.4 eV. The B$_{80}$ cage has rather large electron affinity of 3 eV making it useful candidate as electron acceptor if it is synthesized. The infra-red and Raman spectra of the highly symmetric structure are characterized by a few absorption peaks.
Magnetism in carbon nanostructures is of high scientific interest, which could lead to novel magnetic materials. The magnetic properties of symmetrical and asymmetrical sized small fullerene dimers have been investigated using spin polarized density functional theory. The interaction energies depict that small fullerene cages form stable dimer structures and symmetrical sized fullerene dimers are found more stable than asymmetrical sized dimers. The dimerization of fullerene cages in different modes leads to change in their magnetic properties. The non-magnetic fullerene cages become magnetic …
In this study, based on density functional theory (DFT), we propose a new branch of pseudo-fullerenes which contain triple bonds with sp hybridization. We should call these new nanostructures fullerynes, according to IUPAC. We present four samples with the chemical formula of C4nHn, and structures derived from fullerenes. We compare the structural and electronic properties of these structures with those of two common fullerene and fullerene systems. The calculated electron affinities of the sampled fullerynes are negative, and much smaller than those of fullerenes, so they should be chemically…
Efforts toward stabilization of the Si$_{20}$ fullerene through different schemes have failed despite several theoretical predictions. However, recently Tillmann {\it et. al.} succeeded to stabilize the Si$_{20}$ fullerene through exohedral decoration with eight Cl substituents and twelve SiCl$_3$ groups on the surface and enclosing Cl$^-$ ion. A deeper understanding on what factors lead to stabilization will open the path for stabilizing other systems of interest. Here, we employ the minima hopping method within density functional theory to understand the potential energy surface. The study s…
We have combined ab initio molecular dynamics with the intrinsic reaction coordinate in order to investigate the mechanisms of stability and pyrolysis of N$_{4}$-- N$_{120}$ fullerene-like nitrogen cages. The stability of the cages was evaluated in terms of the activation barriers and the activation Gibbs energies of their thermal-induced breaking. We found that binding energies, bond lengths, and quantum-mechanical descriptors failed to predict the stability of the cages. However, we derived a simple topological rule that adjacent hexagons on the cage surface resulted in its instability. For …
Fully analytic implementation of density functional theory for efficient calculations on large molecules
碳和其他无机材料的类富勒烯笼和纳米管由于其可能的技术应用而目前正处于紧张的研究中。这些材料的第一原理模拟由于大量的原子而在计算上具有挑战性。我们最近开发了一种快速，变分和完全解析的密度泛函理论（ADFT）为基础的模型，允许研究系统大于那些可以使用现有的密度泛函模型进行研究。使用极化高斯基组（6- 311 G **）和ADFT，我们优化了包含超过2000个原子的碳，氮化硼和氮化铝的大富勒烯，富勒烯状笼和纳米管的几何形状。使用近39000个轨道基函数计算C2160是迄今为止在该理论水平上报道的任何孤立分子的最大计算，并且它包括完整的几何优化。研究了无机笼和其他碳富勒烯的电子结构相关性质。
The study of nanostructures' vibrational properties is at the core of nanoscience research, they are known to represent a fingerprint of the system as well as to hint the underlying nature of chemical bonds. In this work we focus on addressing how does the vibrational density of states (VDOS) of the carbon fullerene family ($C_n:~n=20\to720$ atoms) evolves from the molecular to the bulk material (graphene) behavior using density functional theory. We found that the fullerene's VDOS smoothly converges to the graphene characteristic shape-line with the only noticeable discrepancy in the frequenc…
Endohedral Derivatives of the Recently Synthesized Two-Dimensional Fullerene Networks: Electronic and Optical Insights from First-Principles Calculations
The electron-phonon coupling of a theoretically devised carbon phase made by assembling the smallest fullerenes C$_{20}$ is calculated from first principles. The structure consists of C$_{20}$ cages in an {\it fcc} lattice interlinked by two bridging carbon atoms in the interstitial tetrahedral sites ({\it fcc}-C$_{22}$). The crystal is insulating but can be made metallic by doping with interstitial alkali atoms. In the compound NaC$_{22}$ the calculated coupling constant $λ/N(0)$ is 0.28 eV, a value much larger than in C$_{60}$, as expected from the larger curvature of C$_{20}$. On the basis …
Structural, electronic, thermal and mechanical properties of C60-based fullerene two-dimensional networks explored by first-principles and machine learning
First-principles investigation of organic photovoltaic materials C$_{60}$, C$_{70}$, [C$_{60}$]PCBM, and bis-[C$_{60}$]PCBM using a many-body $G_0W_0$-Lanczos approach
