Ab initio and DFT studies on structure, vibrational spectra of 4-tert-butyl-1,3-thiazol-2-amine (BTA)

Theoretical studies have been carried out on 4-tert-butyl-1, 3-thiazol-2-amine (BTA) using both the B3LYP/6-311+G and HF/6-311+G methods. The geometrical parameters and vibrational spectra of BTA have been calculated and analyzed. The calculated IR wavenumbers have been compared with the observed FTIR wavenumbers. The complete assignments have been performed based on the potential energy distribution (PED) of the vibrational modes. The wavenumbers obtained from B3LYP method are in good agreement with the observed wavenumbers when compared to HF method. It has been found that there is an excellent correlation with 0.999 regression coefficient between the experiment and calculated vibrations. Thermal properties like rotational constants, zero point vibrational energies and nonlinear optical properties like dipole moment, hyperpolarizabilities, NBO analysis and the effect of temperature on various thermodynamic properties have been calculated and orted

Structural and spectral studies on benzoyl Thiourea based on DFT calculations

The experimental and theoretical vibrational spectra of benzoyl thiourea were investigated. The experimental FT-IR (400–4000 cm−1) and FT-Raman spectra (100–4000 cm−1) of the molecule in the powder form were recorded. Theoretical vibrational frequencies and geometric parameters (bond lengths and bond angles) were calculated using density functional B3LYP method with 6-311G++(d,p) and cc-pVDZ  basis sets by Gaussian program, for the first time. The complete assignments were performed on the basis of the potential energy distribution (PED) of the vibrational modes, calculated with scaled quantum mechanical (SQM) method. The formation of the hydrogen bond was investigated using NBO calculations. The electron density-based local reactivity descriptors such as Fukuifunctions were calculated. The calculated HOMO and LUMO energies show that charge transfer occur within the molecule. The dipole moment (μ) and polarizability (α), anisotropy polarizability (Δα) and first order hyperpolarizability (βtotal) of the molecule have been reporte

Electronic structure of molecules : studies by photoelectron spectroscopy and ab initio calculations

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Density Functional Theory

Density Functional Theory (DFT) is a powerful technique for calculating and comprehending the molecular and electrical structure of atoms, molecules, clusters, and solids. Its use is based not only on the capacity to calculate the molecular characteristics of the species of interest but also on the provision of interesting concepts that aid in a better understanding of the chemical reactivity of the systems under study. This book presents examples of recent advances, new perspectives, and applications of DFT for the understanding of chemical reactivity through descriptors forming the basis of Conceptual DFT as well as the application of the theory and its related computational procedures in the determination of the molecular properties of different systems of academic, social, and industrial interest

Quantum Computational Investigation of (E)-1-(4-methoxyphenyl)-5-methyl-N?-(3-phenoxybenzylidene)-1H-1,2,3-triazole-4-carbohydrazide

The title compound was synthesized and structurally characterized. Theoretical IR, NMR (with the GIAO technique), UV, and nonlinear optical properties (NLO) in four different solvents were calculated for the compound. The calculated HOMO–LUMO energies using time-dependent (TD) DFT revealed that charge transfer occurs within the molecule, and probable transitions in the four solvents were identified. The in silico absorption, distribution, metabolism, and excretion (ADME) analysis was performed in order to determine some physicochemical, lipophilicity, water solubility, pharmacokinetics, drug-likeness, and medicinal properties of the molecule. Finally, molecular docking calculation was performed, and the results were evaluated in detai

Utilizing High Throughput Computing Techniques for the Predictions of Spectroscopic Properties of Astrophysically Relevant Molecules

Here, we utilize Quantum Chemistry (QC) approaches to predict the structures, vibrational frequencies, infrared intensities and Raman activities of unusual molecular species using the General Atomic and Molecular Structure System (GAMESS(US)) package. A Python-based software, AutoGAMESS, was developed to automate the workflow and take advantage of High Throughput Computing (HTC) techniques enabling the automated generation of spectroscopic data from hundreds of calculations. This approach was utilized to determine these properties for a series of carbon oxides (C2On; n = 3 to 4), anticipated to be produced during the radiation of pure carbon dioxide ices, under conditions relevant to the interstellar medium. Beyond generating predicted spectroscopic results, we additionally performed a benchmark study of 70 different basis sets across multiple levels of theory (including Density Functional Theory, Moller–Plesset, and Coupled Cluster calculations), in QC to identify the method with the best balance between obtaining the lowest error in predictions while being mindful of the computation resources required