Structure and Vibrational Spectrum of Some Polycyclic Aromatic Compounds Studied by Density Functional Theory. 1. Naphthalene, Azulene, Phenanthrene, and Anthracene†

1996 ◽  
Vol 100 (38) ◽  
pp. 15358-15367 ◽  
Author(s):  
Jan M. L. Martin ◽  
Jamal El-Yazal ◽  
Jean-Pierre François
Keyword(s):  
Density Functional Theory ◽  
Vibrational Spectrum ◽  
Aromatic Compounds ◽  
Density Functional ◽  
Polycyclic Aromatic Compounds ◽  
Functional Theory ◽  
Polycyclic Aromatic

scholarly journals Thermodynamic and Theoretical Study of the Preparation of New Buckyballs from Corannulene, Coronene, and Circulene

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Hasan R. Obayes ◽  
Ghadah H. Alwan ◽  
Ahmed A. Al-Amiery ◽  
Abdul Amir H. Kadhum ◽  
Abu Bakar Mohamad
Keyword(s):  
Aromatic Compounds ◽  
Density Functional ◽  
Theoretical Study ◽  
Energy Levels ◽  
Polycyclic Aromatic Compounds ◽  
Functional Theory ◽  
Gap Energy ◽  
Hydrogen Molecules ◽  
Polycyclic Aromatic ◽  
Molecular Dimensions

We applied density functional theory (DFT) to study three polycyclic aromatic compounds (PAHs), corannulene, coronene, and circulene, for the preparation of twelve new buckyballs with molecular dimensions of less than a nanometer. The results showed that the corannulene molecule is bowl-shaped, the coronene molecule is planar, and the circulene molecule has a unique saddle-shaped structure. Cyclic polymerization of the three molecules can be used to prepare new buckyballs, and this process produces hydrogen molecules. The most symmetric buckyball is also the most stable based on the values of the HOMO energy levels and has the most efficient gap energy, making it potentially useful for solar cell applications.

Adsorption of UF6on Graphene Derivatives: a Computational Study of Conditions for 2D Enrichment

2014 ◽  
Vol 1683 ◽  
Author(s):  
Yang Wei Koh ◽  
Kenneth Westerman ◽  
Sergei Manzhos
Keyword(s):  
Density Functional Theory ◽  
Surface Modification ◽  
Laser Radiation ◽  
Vibrational Spectrum ◽  
Density Functional ◽  
Computational Study ◽  
Density Functional Theory Study ◽  
Functional Theory ◽  
Graphene Derivatives ◽  
Isotopic Separation

ABSTRACTWe present a computational density functional theory study of UF6 adsorption on ideal as well as hydrogenated and fluorinated graphene. We show that (i) the isotopic splitting in the vibrational spectrum of UF6 observed in vacuum is largely preserved in the adsorbed molecules. The existence of several adsorption configurations with competing Eads leads to overlaps in the vibrational spectra of isotopomers, but isotopomer-unique modes exist on all three surfaces. (ii) The adsorption energy of UF6 is of the order of 1.2 eV on ideal graphene, 1 eV on graphane, and 0.1 eV on fluorographene, i.e. the adsorption strength is moderate and can be controlled by surface modification. (i) and (ii) mean that it may be possible to cause desorption of a selected isotopomer by laser radiation, leading to isotopic separation between the surface and the gas.

Aromaticity in pericondensed cyclopenta-fused polycyclic aromatic hydrocarbons determined by density functional theory nucleus-independent chemical shifts and the Y-rule — Implications in oil asphaltene stability

2009 ◽  
Vol 87 (10) ◽  
pp. 1280-1295 ◽  
Author(s):  
Yosadara Ruiz-Morales
Keyword(s):  
Density Functional Theory ◽  
Thermodynamic Stability ◽  
Density Functional ◽  
Chemical Shifts ◽  
Functional Theory ◽  
Electronic Distribution ◽  
Polycyclic Aromatic ◽  
Minimum Number ◽  
The Stability ◽  
The One

The characterization of the stability of the fused aromatic region (FAR) in oil asphaltenes in terms of kinetic and thermodynamic stability is primary. Such an understanding is important if we are to get the optimal use from the heavy fraction of any crude oil. The FAR region is composed of pericondensed cyclopenta-fused polycyclic aromatic hydrocarbon compounds (CPPAHs) with N, S, and O heteroatoms. The Clar model, which states that the most important representation of a PAH is one having the maximum number of disjoint π-sextets, depicted by inscribed circles, and a minimum number of fixed double bonds, captures the essence of the kinetic and thermodynamic stability arguments. This model is readily employed for complex aromatics of the sort to be considered for asphaltenes. In the present research we prove that the aromaticity of CPPAHs can be assessed by using the qualitative easy-to-apply Y-rule. In the literature, it is proven that the Y-rule is applicable to elucidate the aromaticity of benzenoid PAHs and it has been validated for pericondensed benzenoid PAHs but not for pericondensed CPPAHs. Here, we verify that it is applicable for CPPAHs. The applicability of the Y-rule has been theoretically proven by comparing the π-electronic distribution obtained with it with the one obtained from nucleus-independent chemical shift (NICS) calculations at the density functional theory (DFT) level. The importance of doing this is that due to the polydispersity in the composition of the oil asphaltenes, and to understand their aromatic core structure, it is necessary to be able to asses the aromaticity of many cyclopenta-fused PAHs (possibly more than 500), of different sizes (up to 15 rings between hexagons and pentagons), and different spatial rearrangements in a quick but realistic and effective way. To try to do this with NICS will be very time consuming and computationally expensive, especially in the case of big systems.

scholarly journals DFT and TD-DFT Study of Structure and Properties of Semiconductive Hybrid Networks Formed by Bismuth Halides and Different Polycyclic Aromatic Ligands

2011 ◽  
Vol 8 (s1) ◽  
pp. S195-S202
Author(s):  
Y. Belhocine ◽  
M. Bencharif
Keyword(s):  
Density Functional Theory ◽  
Band Gap ◽  
Density Functional ◽  
Relativistic Effects ◽  
Spectroscopic Properties ◽  
Basis Set ◽  
Dft Methods ◽  
Functional Theory ◽  
Td Dft ◽  
Polycyclic Aromatic

The structure and spectroscopic properties of polycyclic aromatic ligands of 2,3,6,7,10,11-hexakis (alkylthio) triphenylene (alkyl: methyl, ethyl, and isopropyl; corresponding to the abbreviations of the molecules: HMTT, HETT and HiPTT) were studied using density functional theory (DFT) and time dependent density functional theory (TD-DFT) methods with triple-zeta valence polarization (TZVP) basis set. It was shown that the type of functional theory used, Becke-Perdew (BP) and Leeuwen-Baerends (LB94) implemented in Amsterdam Density functional (ADF) program package, does not have essential influence on the geometry of studied compounds in both ground and excited states. However, significant differences were obtained for the band gap values with relativistic effects of the zero order regular approximation scalar corrections (ZORA) and LB94 functional seems to reproduce better the experimental optical band gap of these systems.

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