Vibrational frequency analysis of CH3Cl molecule; ab initio study (original) (raw)
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2015
The infrared spectra of CH3Cl + H2O isolated in solid neon at low temperatures have been investigated. The CH3Cl + H2O system is remarkable because of its propensity to form CH3Cl:H2O and CH3Cl:(H2O)n (n g 2) complexes. We focus here on the CH3Cl:H2O species. Low concentration studies (0.01-0.5%) and subsequent annealing lead to formation of the 1:1 CH3Cl:H2O complex with O-Hâ â âCl-C or Oâ â âH-C intermolecular hydrogen bonds. Vibrational modes of this complex have been detected. In addition, spectra of D2O + CH3Cl and HDO + CH3Cl have also been recorded. A detailed vibrational analysis of partially deuterated species shows that HDO is exclusively D bonded to CH3Cl. This is a consequence of the preference for HDO to form a deuterium bonding complex rather than a hydrogen bonding one.
Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, 2012
FT-IR and FT-Raman spectra of α,α,α-trichlorotoluene have been recorded and analyzed. The geometry, fundamental vibrational frequencies are interpreted with the aid of structure optimizations and normal coordinate force field calculations based on density functional theory (DFT) B3LYP/6-311++G(d,p) method and a comparative study between HF level and various basis sets combination. The fundamental vibrational wavenumbers as well as their intensities were calculated and a good agreement between observed and scaled calculated wavenumbers has been achieved. The complete vibrational assignments of wavenumbers are made on the basis of potential energy distribution (PED). The effects due to the substitutions of methyl group and halogen were investigated. The absorption energy and oscillator strength are calculated by time-dependent density functional theory (TD-DFT). The electric dipole moment, polarizability and the first hyperpolarizability values of the α,α,α-trichlorotoluene have been ...
Polymer Bulletin
The density functional theory calculation has been carried out for the analysis of 5-chlorouracil using DFT/Gaussian 09 with GAR2PED. Recorded experimental spectra for Raman and IR of 5-chlorouracil have been analyzed all fundamental vibrational modes using the outcome results of DFT at 6-311++G** of Gaussian 09 calculations and the GaussView 5.09. To help the analysis of vibrational modes, GAR2PED program has been used in the calculation of PEDs. The charge transfer properties of 5-chlorouracil have been analyzed using HOMO and LUMO level energy analysis. HOMO and LUMO energy gap study supports the charge transfer possibility in molecule. These have been made to study for reactivity and stability of heterocyclic molecules for the analysis of antiviral drugs against the new corona virus: COVID-19. Here, the smaller energy gap of 5-chlorouracil is more responsible for charge transfer interaction in the heterocyclic drug molecules and a reason of more bioactivity. The electron density mapping within molecular electrostatic potential plot and electrostatic potential plotting within iso-surface plot have been evaluated the charge distribution concept in the molecule as the nucleophilic reactions and electrophilic sites. These computations have been used to produce the molecular charges, structure and thermodynamic functions of biomolecule. This study has been made to all internal modes of chloro group substituent at pyrimidine ring of C 5 atom. The splitting of frequencies has arisen in the two species for the normal distribution modes.
Journal of physical chemistry and functional materials, 2019
In this study, the chemical reactivity, stability and electronic properties of Propylbenzene (C9H12) and 2-chloro-5-(trifluoromethyl) aniline (C7F3NH5Cl) molecules have been investigated by using the Density Functional Theory (DFT) and Hartree Fock Theory (HFT) methods with difference basis sets like (B3LYP/3-21G, 6-31+G(dp), 6-31G,6-311G). The Lowest Unoccupied Molecular Orbitals (LUMO), and Highest Occupied Molecular Orbitals (HOMO) energies can be used to characterize the kinetic stability and chemical reactivity in chemical structure for these molecules.
Ab initio HF and DFT simulations, FT-IR and FT-Raman vibrational analysis of α-chlorotoluene
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2010
The FT-IR and FT-Raman vibrational spectra of ␣-chlorotoluene have been recorded using Perkin-Elmer 180 spectrometer in the range 3600-10 cm −1 in the solid phase. A detailed vibrational spectral analysis has been carried out and assignments of the observed fundamental bands have been proposed on the basis of peak positions and relative intensities. The optimized molecular geometry, vibrational frequencies, atomic charges, dipole moment, rotational constants and several thermodynamic parameters in the ground state were calculated using ab initio Hartree-Fock (HF) and Density Functional B3LYP methods (DFT) with 6-311G(d) and 6-311++G(d) basis sets. With the help of specific scaling procedures, the observed vibrational wavenumbers in FT-IR and FT-Raman spectra were analyzed and assigned to different normal modes of the molecule. Most of the modes have wavenumbers in the expected range. The results of the calculations were applied to simulated infrared and Raman spectra of the title compound which showed excellent agreement with the observed spectra.
Study of the vibrational spectra of (CH 3 ) 3 GeCl from experimental and DFT calculations
Journal of Raman Spectroscopy, 2009
New infrared (for gas and liquid phase) and Raman (for liquid) spectra were measured for the chlorotrimethylgermane to obtain a complete assignment of its fundamental modes. The measurement of the low-temperature infrared spectrum together with the application of Fourier self-deconvolution to the Raman spectra resolves the C-H vibrational modes into their components. The Rauhut and Pulay scaled quantum mechanical (SQM) force field methodology and the wavenumber-linear scaling (WLS) method were used to predict the vibrational spectra as a guide to the assignment of the fundamental bands. A quantum mechanical analysis was carried out to obtain the harmonic force field.
Russian Chemical Bulletin, 2005
The structures of isotopomers of conformationally flexible acetyl chloride molecule, CH3COCl and CD3COCl, in the ground (S0 and lowest excited singlet (S1) and triplet (T1) electronic states were calculated by the RHF, MP2, and CASSCF methods. The equilibrium geometric parameters and harmonic vibrational frequencies of the molecules in these electronic states were estimated. According to calculations, electronic excitation causes considerable conformational changes involving rotation of the CH3 (CD3) top and a substantial deviation of the CCOCl fragment from planarity. The results of calculations agree with experimental data. Two dimensional torsional inversion sections of the potential energy surface were calculated and analyzed. Vibrational problems for large amplitude vibrations (torsional vibration in the S0 state and both torsional and inversion vibrations in the T1 and S1 states) were solved in one- and two-dimensional approximations.