15 research outputs found
First-principles calculations of the structural, electronic, vibrational and magnetic properties of C_{60} and C_{48}N_{12}: a comparative study
In this work, we perform first-principles calculations of the structural,
electronic, vibrational and magnetic properties of a novel azafullerene. Full geometrical optimization shows that is characterized by several distinguishing features: only
one nitrogen atom per pentagon, two nitrogen atoms preferentially sitting in
one hexagon, symmetry, 6 unique nitrogen-carbon and 9 unique
carbon-carbon bond lengths. The highest occupied molecular orbital of is a doubly degenerate level of symmetry and its
lowest unoccupied molecular orbital is a nondegenerate level of
symmetry. Vibrational frequency analysis predicts that has in total 116 vibrational modes: 58 infrared-active and 58
Raman-active modes. is also characterized by 8
and 2 NMR spectral signals. Compared to , shows an enhanced third-order optical
nonlinearities which implies potential applications in optical limiting and
photonics.Comment: a long version of our manuscript submitted to J.Chem.Phy
First-principles calculations of structural, electronic, vibrational, and magnetic properties of C60 and C48N12: A comparative study
The structural, electronic, vibrational, and magnetic properties of the C 48 N 12 azafullerene and C 60 are comparatively studied from the first-principles calculations. Full geometrical optimization and Mulliken charge analysis are performed. Electronic structure calculations of C 48 N 12 show that the highest occupied molecular orbital (HOMO) is a doubly degenerate level of a g symmetry and the lowest unoccupied molecular orbital (LUMO) is a nondegenerate level of a u symmetry. The calculated binding energy per atom and HOMO-LUMO energy gap of C 48 N 12 are about 1 eV smaller than those of C 60 . Because of electron correlations, the HOMO-LUMO gap decreases about 5 eV and the binding energy per atom increases about 2 eV. The average second-order hyperpolarizability of C 48 N 12 is about 55% larger than that of C 60 . Our vibrational frequency analysis predicts that C 48 N 12 has 58 infrared-active and 58 Raman-active vibrational modes. Two different methods for calculating nuclear magnetic shieldingtensors of C 60 and C 48 N 12 are compared, and we find that C 48 N 12 exhibits eight 13 C and two 15 N NMRspectral signals. Our best-calculated results for C 60 are in excellent agreement with experiment. Our results suggest that C 48 N 12 has potential applications as semiconductor components, nonlinear optical materials, and possible building blocks for molecular electronics and photonic devices
Electronic, vibrational and magnetic properties of a novel C_{48}N_{12} aza-fullerene
We study the structural, electronic, vibrational and magnetic properties of a
novel aza-fullerene using density functional theory
and restricted Hartree-Fock theory. Optimized geometries and total energy of
this fullerene have been calculated. We find that for the total ground state energy is about -67617 eV, the HOMO-LUMO gap is
about 1.9 eV, five strong IR spectral lines are located at the vibrational
frequencies, 461.5 , 568.4 , 579.3 , 1236.1 , 1338.9 , the Raman scattering
activities and depolarization ratios are zero, and 10 NMR spectral signals are
predicted. Calculations of diamagnetic shielding factor, static dipole
polarizabilities and hyperpolarizabilities of are
performed and discussed.Comment: published in Chem.Phys.Let
Tailorable Acceptor C 60 − n B n and Donor C 60 − m N m Pairs for Molecular Electronics
Our first-principles calculations demonstrate that C 60-n B n /C 60-m Nm molecules could be engineered acceptor/donor pair needed for molecular electronics by properly controlling the number n and m of the substitutional dopants in C 60 . As an example, we propose that acceptor C 48 B 12 and donor C48 N12 can be promising components for molecular rectifiers, nanotube-based p-type, n-type and n-p-n transistors and p-n junctions
Raman scattering in C_{60} and C_{48}N_{12} aza-fullerene: First-principles study
We carry out large scale {\sl ab initio} calculations of Raman scattering
activities and Raman-active frequencies (RAFs) in
aza-fullerene. The results are compared with those of .
Twenty-nine non-degenerate polarized and 29 doubly-degenerate unpolarized RAFs
are predicted for . The RAF of the strongest Raman
signal in the low- and high-frequency regions and the lowest and highest RAFs
for are almost the same as those of .
The study of reveals the importance of electron correlations and
the choice of basis sets in the {\sl ab initio} calculations. Our best
calculated results for with the B3LYP hybrid density functional
theory are in excellent agreement with experiment and demonstrate the desirable
efficiency and accuracy of this theory for obtaining quantitative information
on the vibrational properties of these molecules.Comment: submitted to Phys.Rev.