Computational Physics

Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TD-DFT) were treated according to Becke’s three Lee–Yang–Parr (B3LYP) correlation potential due to its less error value than other functionals. This molecule has biological studies are useful for fields, due to its thermal stability and less energy bang gap of probe has luminescence applications.

The molecular geometry, vibrational frequencies of 3-(trifluromethyl) phenyl isothiocyanate in the ground state have been analyzed using density functional theory calculation (B3LYP) with 6-311++G (d,p) and 6-311++G (2d,2p) basis sets. The optimized geometrical parameters obtained by DFT calculations are in good agreement with experimental values. Comparison of the observed fundamental vibrational frequencies of the 3-(trifluromethyl) phenyl isothiocyanate and calculated result by DFT/B3LYP/6-311++G(d,p)/6-311++G (2d,2p) is superior for molecular vibrational problems. A detailed interpretation of the FTIR and FT-Raman spectra of 3-(trifluromethyl) phenyl isothiocyanate are reported on the basis of the calculated potential energy distribution (PED).

In this study a quick summary for the back-hole theory was presented. It was presented earlier in from of graduation project at university of Bahri, college of applied and industrial sciences department of physics, Khartoum, Sudan by the second author and under supervision of the first author. Black holes were once a star shining for years, before eventually collapse on their core forming the BH. There are three cases for a star non stable end is either a white dwarf, a neutron star or a black hole which is completely depend on the mass of the previous star which are called a compact star due to their highly condensation states. In this paper a quick summary for the theory was presented.

Over several years, 5-Nitro 2-Furaldehyde Semicarbozone, otherwise known as Nitrofurazone has been in widespread use as anti-bacterial drug. The recording of FTIR and Laser Raman Spectra is done for the characteristic vibrations of C=N, N-N and furan ring systems and the tentative vibrational assignments have been reported. In the present investigation, vibrational assignments has been carried out for the molecule of the title compound using fundamental modes of vibration observed in Infrared and Raman Spectroscopy. The vibrational modes are classified into a’ and a” irreducible representations. Thus 42 fundamental modes of vibration ie.29a’ and 13a” vibrations are considered. A satisfactory vibrational band assignment has been made by using the FTIR Laser Raman Spectra of the compound.

Normal coordinate calculations of Adenine have been carried out using Wilson’s FG matrix mechanism on the basis of General Valence Force Field (GVFF) for both in-plane and out-of-plane vibrations. The potential energy constants obtained in this study are refined using numerical methods. A satisfactory vibrational band assignment has been made by using FT-IR and FT-Raman spectra of the title compound.

Ultrasonic velocity (U), viscosity (?) and density (?), were measured for liquid mixtures of Brompheniramine and1-pentanol at 303,308 and 313K. Adiabatic compressibility (?), viscous relaxation time (?), free volume (Vf), free length (Lf), and Gibbs free energy (?G) were determined. Excess values of that parameters (?E, LfE , Vf E ,?E and ?GE ) also calculated and elucidated in terms of intermolecular interaction like hydrogen bond between selected liquid system. It was observed that homo and hetero association of molecules decreased with the temperatures.

Variation is an important mathematical physics method in mathematical physics problem. Many physical problems are always concerned with variation, and they can be solved by extremum of functional. We can obtain physical laws by way of variation calculus, such as the solution of problems of central field and electromagnetic field. By application of calculus of variation, the motion of matter can be unified.

In this article computational study by using DFT on Exalite – 392A is reported. The quantum mechanical analysis of various energies of molecule in ground state was calculated by using DFT technique. The effect of the solvent on optimized geometry, Mulliken charge distribution in ground and excited state were analysed. With the help of computed highest occupied molecular orbital (HOMO) - lowest unoccupied molecular orbital (LUMO) gap of Exalite – 392A in different medium, we can analysed solvation energy, ionization potential, electron affinity, chemical hardness, electron chemical potential, electronegativity and global electrophilic. UV-Vis spectrum was obtained by using TDDFT technique. The total electron density (TED), potential distribution over molecule by electrostatic potential (ESP) positions of molecule were obtained from molecular electrostatic potential (MEP) and frontier molecular orbitals (FMO) simulated. Main objective is to determine their electronic, thermodynamic and spectroscopic parameters on the basis of the DFT quantum chemical studies and also we are studying the effect of solvent and solute-solvent interactions. This molecule is helpful in designing of lasers.

The molecular vibrations of 1-Naphthol were investigated in polycrystalline sample, at room temperature, by FT- IR and FT-Raman spectroscopy. In parallel, ab initio and various density functional (DFT) methods were used to determine the geometrical, energetic and vibrational characteristics of 1-Naphthol. On the basis of B3LYP/6-31G* and B3LYP/6-311+G** methods and basis set combinations, a normal mode analysis was performed to assign the various fundamental frequencies according to the total energy distribution (TED). The vibrational spectra were interpreted, with the aid of normal coordinate analysis based on a scaled quantum mechanical force field. The Infrared and Raman spectra were also predicted from the calculated intensities. Comparison of simulated spectra with the experimental spectra provides important information about the ability of the computational method to describe the vibrational modes. Simulation of Infrared and Raman spectra, utilizing the results of these calculations led to excellent overall agreement with observed spectral patterns.The investigation is performed using quantum chemical calculations conducted by means of the Gaussian 98W and Guassview set of programs. Further, density functional theory (DFT) combined with quantum chemical calculations to determine the first-order hyperpolarizability.

This work focused onan integrated approach of solutions to improve the combustion of Jatropha oil in an indirect injection Diesel engine (Lister type). The improvements were assessed using combustion parameters, especially cyclic dispersion.The Jatropha oil was preheated to 100°C and the Diesel engine has receivedchanges in fuel injection timing and injection pressure variation. The overall engine performance (specific fuel consumption, thermal efficiency and exhaust gas temperatures), cyclic dispersion, ignition delays obtained with Jatropha oil and Diesel fuel were compared. The results show that for the performance, the injection timing of 20 Crank Angle (CA) Before Top Dead Center (BTDC) and the injection pressure of 170 bars are the settings adapted for both fuels to the different engine loads. The results also show that cyclic dispersion could be used as a very good tool for assessment of adequateoperating conditions of this type of engine, even at low loads. The cyclic dispersion is low with coefficients of variation of the indicated mean effective pressure (COVIMEP) whose values are less than 10%. The lowest values of the COVIMEP are obtained when the injection settings are 20 CA BTDC and 170 bars.