Simulations of Graphene Sheets Based on the Finite Element Method and Density Functional Theory: Comparison of the Geometry Modeling under the Influence of Defects

In the present research, imperfect graphene sheets were generated and their vibrational property was studied via finite element analysis. The effect of vacant sites in the arrangement of these nano-structures was examined. The fundamental frequency of the defect free and imperfect nano-sheets was acquired based on two different approaches. The first approach was a pure finite element simulation. The second approach for comparison purpose was a recently reported refined finite element simulation at which the vicinity of a defect was first evaluated according to the density functional theory (DFT) and then the refined geometry was implemented into a finite element model. The findings of this research show that the fundamental frequency of graphene sheets decreases by presenting microscopic imperfection to the formation of these nano-materials. In addition, it was pointed out that the geometry based on the more precise DFT simulations gives a higher decrease in the fundamental frequency of the sheets for all considered cases.

The Geometry Structure and Molecular Vibrational Property of the Zeatin

Zeatin belongs to the derivation of purine, and the C=C is one of the functional groups in the zeatin structure. So, there are trans- and cis- structures for the zeatin molecule. Interestingly, the trans-zeatin has biological activities, but the cis-zeatin has no obvious biological activity. The trans-zeatin is the first separated cell cytokinins from the plant tissue. And the zeatin, especially trans-zeatin has important and extensive applications in many research fields. In this study, the Geometries of the trans-zeatin and cis-zeatin were optimized by using the density function Becke, three-parameter, Lee-Yang-Parr, DFT/B3LYP/6-31G method. Additionally, FT-IR experiments were conducted for the trans-zeatin. The geometry structures and molecular vibrational property of the zeatin were simply discussed.

Scaled Quantum FT-IR and FT-Raman Spectral Analysis of 1-Methoxynaphthalene

The structural and vibrational property of 1-methoxynaphthalene has been studied. The fundamental vibrational frequencies and intensity of vibrational bands were evaluated using B3LYP/6-31G (d, p) basis set and was scaled using various scale factors, which yielded a good agreement between observed and calculated frequencies. The vibrational spectra were interpreted with the aid of normal coordinate analysis. The results of the calculations were applied to simulated spectra of the title compound, which shows excellent agreement with observed spectra. The calculated force constants in vibrational internal coordinates are in closely coincides with the experimentally observed force constants.