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Optimized geometry, vibration (IR and Raman) spectra and nonlinear optical activity of p-nitroanilinium perchlorate molecule: A theoretical study

Tamer O., Atalay A. S., Avci D., Atalay Y., Tarcan E., Marchewka M. K.

Materials Science Poland

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2016

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Vol. 34, No. 1

192--203

EN

The molecular modeling of p-nitroanilinium perchlorate molecule was carried out by using B3LYP and HSEH1PBE levels of density functional theory (DFT). The IR and Raman spectra were simulated and the assignments of vibrational modes were performed on the basis of relative contribution of various internal co-ordinates. NBO analysis was performed to demonstrate charge transfer, conjugative interactions and the formation of intramolecular hydrogen bonding interactions within PNAPC. Obtained large dipole moment values showed that PNAPC is a highly polarizable complex, and the charge transfer occurs within PNAPC. Hydrogen bonding and charge transfer interactions were also displayed by small HOMO-LUMO gap and molecular electrostatic potential (MEP) surface. The strong evidences that the material can be used as an efficient nonlinear optical (NLO) material of PNAPC were demonstrated by considerable polarizability and hyperpolarizability values obtained at DFT levels.

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Quality Evaluation of Remelted A356 Scraps

Yuksel C., Tamer O., Erzi E., Aybarc U., Cubuklusu E., Topcuoglu O., Cigdem M., Dispinar D.

Archives of Foundry Engineering

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2016

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Vol. 16, iss. 3

151--156

EN

A356 is one of the widely used aluminium casting alloy that has been used in both sand and die casting processes. Large amounts of scrap metal can be generated from the runner systems and feeders. In addition, chips are generated in the machined parts. The surface area with regard to weight of chips is so high that it makes these scraps difficult to melt. Although there are several techniques evolved to remedy this problem, yet the problem lies in the quality of the recycled raw material. Since recycling of these scrap is quite important due to the advantages like energy saving and cost reduction in the final product, in this work, the recycling efficiency and casting quality were investigated. Three types of charges were prepared for casting: %100 primary ingot, %100 scrap aluminium and fifty-fifty scrap aluminium and primary ingot mixture were used. Melt quality was determined by calculating bifilm index by using reduced pressure test. Tensile test samples were produced by casting both from sand and die moulds. Relationship between bifilm index and tensile strength were determined as an indication of correlation of melt quality. It was found that untreated chips decrease the casting quality significantly. Therefore, prior to charging the chips into the furnace for melting, a series of cleaning processes has to be used in order to achieve good quality products.

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A theoretical study on 2-chloro-5-(2-hydroxyethyl)-4-methoxy-6-methylpyrimidine by DFT/ab initio calculations

Gumus H. P., Tamer O., Avci D., Atalay Y.

Materials Science Poland

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2015

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Vol. 33, No. 2

369--380

EN

Quantum chemical calculations have been performed to study the molecular geometry, H-1 and C-13 NMR chemical shifts, conformational, natural bond orbital (NBO) and nonlinear optical (NLO) properties of the 2-chloro-5-(2-hydroxyethyl)-4methoxy-6-methylpyrimidine molecule in the ground state using DFT and HF methods with 6-311++G(d,p) basis set. The optimized geometric parameters and H-1 and C-13 NMR chemical shifts have been compared with the experimental values of the title molecule. The results of the calculations show excellent agreement between the experimental and calculated frequencies at B3LYP/6-311++G(d,p) level. In order to provide a full understanding of the properties of the title molecule in the context of molecular orbital picture, the highest occupied molecular energy level (E-HOMO), the lowest unoccupied molecular energy level (E-LUMO), the energy difference (Delta E) between EHOMO and ELUMO, electronegativity (chi), hardness (eta) and softness (S) have been calculated using B3LYP/6-311++G(d, p) and HF/6-311++G(d,p) levels. The calculated HOMO and LUMO energies show that the charge transfer occurs within the title molecule.

4

Quantum chemical computational studies on bis-thiourea zinc acetate

Pir H., Günay N., Tamer O., Avci D., Tarcan E., Atalay Y.

Materials Science Poland

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2013

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Vol. 31, No. 3

357--371

EN

In this study, quantum chemical calculations of vibrational spectra, Raman spectra, electronic properties (total energy, dipole moment, electronegativity, chemical hardness and softness), Mulliken atomic charges and thermodynamic parameters of bis-thiourea zinc acetate (BTZA) have been performed using Gaussian 09 program. Additionally, nonlinear optical (NLO), conformational, natural bond orbital (NBO) analyses of BTZA have been carried out using the same program. The structural and spectroscopic data of the molecule in the ground state have been calculated using Hartree-Fock (HF) and density functional method (DFT/B3LYP) with the 6-311++G(d,p) basis set. In addition, the molecular frontier orbital energies (HOMO, HOMO-1, LUMO and LUMO+1) of the title compound have been calculated at the HF and B3LYP levels. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. Finally, the calculated results were applied to simulate infrared and Raman spectra of the title compound which showed good agreement with the experimental ones.