scholarly journals Molecular Structure, Vibrational Spectra and Chemical Shift Properties of C12H9ClO4 and C12H9BrO4 Crystals by Density Functional Theory and ab initio Hartree-Fock Calculations

2009 ◽  
Vol 64 (11) ◽  
pp. 745-752 ◽  
Author(s):  
Nergin Günay ◽  
Erdogan Tarcan ◽  
Davut Avcı ◽  
Kadir Esmer ◽  
Yusuf Atalay
Keyword(s):  
Molecular Structure ◽  
Chemical Shift ◽  
Vibrational Spectra ◽  
Density Functional ◽  
Atomic Orbital ◽  
Density Functional Method ◽  
Molecular Geometry ◽  
Basis Set ◽  
Gauge Transformations ◽  
Hartree Fock

The molecular geometry, vibrational spectra, and gauge including atomic orbital (GIAO), individual gauges for atoms in molecules (IGAIM), and continuous set of gauge transformations (CSGT) 1H and 13C chemical shift values of ethyl 6-chloro-2-oxo-2H-chromene-3-carboxylate (C12H9ClO4-(I)) and ethyl 6-bromo-2-oxo-2H-chromene-3-carboxylate (C12H9BrO4-(II)) in the ground state have been calculated by using the Hartree-Fock (HF) and density functional method (B3LYP) with 6- 31G+(d,p) basis set. The results of the optimized molecular structure are presented and compared with the experimental X-ray diffraction. The computed vibrational frequencies were used to determine the types of molecular motions associated with the spectra of the experimental bands observed. Also, calculated 1H and 13C chemical shift values were compared with the experimental ones.

scholarly journals NLO and NBO Analysis of Sarcosine-Maleic Acid by Using HF and B3LYP Calculations

2013 ◽  
Vol 2013 ◽  
pp. 1-16 ◽  
Author(s):  
N. Günay ◽  
H. Pir ◽  
D. Avcı ◽  
Y. Atalay
Keyword(s):  
Molecular Structure ◽  
Maleic Acid ◽  
Title Compound ◽  
Density Functional ◽  
Density Functional Method ◽  
Nbo Analysis ◽  
Functional Method ◽  
Basis Set ◽  
Charge Delocalization ◽  
Hartree Fock

We report a theoretical study on molecular structure, vibrational spectra, nonlinear optical (NLO), and natural bond orbital (NBO) analysis of sarcosine-maleic acid (C7H11NO6) in the ground state calculated by using the Hartree-Fock (HF) and density functional method (DFT/B3LYP) with 6–31++G(d,p) basis set. We repeat NBO calculations with 6–31G(d,p) basis set so as to see the diffuse function impact on NBO analysis. Stability of the molecule arising from hyper conjugative interactions and charge delocalization has been analyzed using NBO analysis. NBO analysis shows that there is a O–H⋯O and N–H⋯O hydrogen bond in the title compound, which is consistent with the conclusion obtained by the analysis of molecular structure. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. Also, these results are supported by the NLO parameters. Finally, the calculated results were applied to simulate infrared and Raman spectra of the title compound which showed good agreement with experimental ones.

Density Functional Theory and ab initio Hartree-Fock Calculations of Molecular Structure and Vibrational Spectra of Anilinium Nitrate

2008 ◽  
Vol 63 (10-11) ◽  
pp. 712-720 ◽  
Author(s):  
Davut Avcı ◽  
Adil Başoğlu ◽  
Yusuf Atalay
Keyword(s):  
Molecular Structure ◽  
Density Functional Theory ◽  
Density Functional ◽  
Molecular Geometry ◽  
Vibrational Frequencies ◽  
Basis Set ◽  
Dft Methods ◽  
Functional Theory ◽  
Hartree Fock ◽  
Infrared Intensities

The molecular geometry, vibrational frequencies, infrared intensities, Raman scattering activities and several thermodynamic parameters of anilinium nitrate in the ground state have been calculated by both Hartree-Fock (HF) and three density functional theory (DFT) methods (B3LYP, BLYP and B3PW91) using the 6-31G(d) basis set. The results of the optimized molecular structure are presented and compared with the experimental X-ray structure. The optimized geometric bond lengths are described very well by the HF method while bond angles are reproduced more accurately by the DFT methods. Comparison between the observed fundamental vibrational frequencies of anilinium nitrate and the results of DFT and HF methods indicates that B3LYP is superior to the scaled HF, BLYP and B3PW91 approaches for molecular vibrational problems. The computed vibrational frequencies are used to determine the types of molecular motions associated with each of the experimental bands observed. In addition, calculated results are related to the linear correlation plot of computed data versus experimental geometric parameters and IR data.

scholarly journals Density functional theory study on the molecular structure of loganin

2011 ◽  
Vol 25 (6) ◽  
pp. 287-302 ◽  
Author(s):  
Anoop Kumar Pandey ◽  
Shamoon Ahmad Siddiqui ◽  
Apoorva Dwivedi ◽  
Kanwal Raj ◽  
Neeraj Misra
Keyword(s):  
Molecular Structure ◽  
Density Functional ◽  
Solid Phase ◽  
Density Functional Method ◽  
Functional Method ◽  
Basis Set ◽  
Equilibrium Geometry ◽  
B3lyp Method ◽  
Ft Ir ◽  
Detailed Interpretation

The computational Quantum Chemistry (QC) has been used for different types of problems, for example: structural biology, surface phenomena and liquid phase. In this paper we have employed the density functional method for the study of molecular structure of loganin. The equilibrium geometry, harmonic vibrational frequencies and infrared intensities were calculated by B3LYP/6-311G (d, p) method and basis set combinations. It was found that the optimized parameters obtained by the DFT/B3LYP method are very near to the experimental ones. A detailed conformational analysis was carried out. A detailed interpretation of the infrared spectra of loganin is also reported in the present work. The FT-IR spectra of loganin were recorded in solid phase. The thermodynamic calculations related to the title compound were also performed at B3LYP/6-311G (d, p) level of theory.

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