nan Diwaker

Quantum mechanical and spectroscopic (FT-IR, 13C, 1H NMR and UV) investigations of 2-(5-(4-Chlorophenyl)-3-(pyridin-2-yl)-4,5-dihydropyrazol-1-yl)benzo[d]thiazole by DFT method

The electronic, NMR, vibrational, structural properties of a new pyrazoline derivative: 2-(5-(4-Chlorophenyl)-3-(pyridine-2-yl)-4,5-dihydropyrazol-1-yl)benzo[d]thiazole has been studied using Gaussian 09 software package. Using VEDA 4 program we have reported the PED potential energy distribution of normal mode of vibrations of the title compound. We have also reported the (1)H and (13)C NMR chemical shifts of the title compound using B3LYP level of theory with 6-311++G(2d,2p) basis set. Using time dependent (TD-DFT) approach electronic properties such as HOMO and LUMO energies, electronic spectrum of the title compound has been studied and reported. NBO analysis and MEP surface mapping has also been calculated and reported using ab initio methods.

Multi-channel scattering problems: an analytically solvable model

Nonadiabatic transition due to potential curve crossing is one of the most important mechanisms to effectively induce electronic transitions in collisions [1]. This is a very interdisciplinary concept and appears in various fields of physics and chemistry and even in biology [2–7]. The theory of non-adiabatic transitions dates back to 1932, when the pioneering works for curve-crossing and non-crossing were published by Landau [8], Zener [9] and Stueckelberg [10] and by Rosen and Zener [11] respectively. Osherov and Voronin solved the case where two diabatic potentials are constant with exponential coupling [12]. C. Zhu solved the case where two diabatic potentials are exponential with exponential coupling [13]. In this paper we consider the case of two or more diabatic potentials with Dirac Delta couplings. The Dirac Delta coupling model has the advantage that it can be exactly solved [14–19] if the uncoupled diabatic potential has an exact solution.We have proposed a general method for finding an exact analytical solution for the multi-channel scattering problem in the presence of a delta function coupling. Our solution is quite general and is valid for any set of potentials, if the uncoupled diabatic potential has an exact solution. We have also discussed a few examples, where our method can easily be applied.

Synthesis, spectroscopic characterization, electronic and optical studies of (2Z)‐5,6‐dimethyl‐2‐[(4‐nitrophenyl)methylidene]‐2,3‐dihydro‐1‐benzofuran‐3‐one

The title compound, (2Z)‐5,6‐dimethyl‐2‐[(4‐nitrophenyl) methylidene]‐2,3‐dihydro‐1‐benzo furan‐3‐one, has been synthesized and characterized using experimental (XRD) and theoretical methods (FTIR, NMR, electronic and optical studies). The compound crystallizes in monoclinic space group P21/c with a = 7.527 (7) A, b = 15.9397(15) A, c = 13.5106 (10) A, β = 117.649 (4)° and Z = 4. The initial coordinate geometry obtained by XRD is further used to obtain the optimized ground state geometry of the title compound using DFT/B3LYP/6-311++G (2d,2p) level of theory. Geometrical parameters, vibration frequencies, Gauge invariant atomic orbital (GIAO) 1H and 13C NMR chemical shifts of the title compound have been calculated theoretically using the optimized ground state geometry. Apart from this, density of states of different atoms, band gap studies and optical properties have also been studied successfully using theoretical models.

Curve crossing problem with Gaussian type coupling: analytically solvable model

We give a general method for finding an exact analytical solution for the two state curve crossing problem. The solution requires the knowledge of the Greens function for the motion on the uncoupled potentials. We use the method to find the solution of the problem in the case of parabolic potentials coupled by Gaussian interaction. Our method is applied to this model system to calculate the effect of curve crossing on the electronic absorption spectrum and the resonance Raman excitation profile.

Spectroscopic (FT-IR, 1H, 13C NMR and UV–vis) characterization and DFT studies of novel 8-((4-(methylthio)-2,5-diphenylfuran-3-yl)methoxy)quinoline

In this study, computational calculations of a new quinoline derivative: 8-((4-(methylthio)-2,5-diphenylfuran-3-yl)methoxy)quinoline is carried out using ab initio methods. The geometry optimization as well as fundamental frequencies of the most stable configuration of the title compound is reported. A detailed study of Infrared spectrum, chemical shifts and electronic spectrum of the title compound is also presented. The Gauge-Invariant Atomic Orbital approach is used to calculate the proton and carbon chemical shifts of the title compound. The natural bond orbital analysis of the title compound is also reported in order to understand the stability of the molecule which arises from hyper conjugative interactions and charge delocalization. The theoretical electronic absorption spectrum is also reported using the time dependent density functional approach. The molecular structure along with vibrational frequencies as simulated for binding of iron with the title compound is also reported using ab initio methods.

Quantum Chemical and Spectroscopic Investigations of (Ethyl 4 hydroxy-3-((E)-(pyren-1-ylimino)methyl)benzoate) by DFT Method

In the present work we have reported the optimized ground state geometry, harmonic vibrational frequencies, NMR chemical shifts, NBO analysis, and molecular electrostatic potential surface map of the title compound using DFT/B3LYP/6-311

Transfer matrix approach to the curve crossing problems of two exponential diabatic potentials

In the present manuscript, we have presented a method of calculation of non-adiabatic transition probability using transfer matrix technique. As an example for the two-state curve crossing problem, we have considered two diabatic potentials (two exponential potentials in the present case) with opposite sign of slopes which crosses each other and there is a coupling between the two diabatic potentials. The coupling is chosen as a Gaussian coupling which is further expressed as a collection of Dirac Delta potentials and the transition probability from one diabatic potential to another is calculated.

Spectroscopic (FT-IR, 1H, 13C NMR, UV), DOS and orbital overlap population analysis of copper complex of (E)-4-(2-(4-nitrophenyl) diazenyl)-N, N bis ((pyridin-2-yl) methyl) benzamine by density functional theory

The geometric parameters, chemical shifts, FTIR, NMR and orbital overlap population along with DOS (density of states) to know different kinds of interactions for binding of copper atom with (E)-4-(2-(4-nitrophenyl) diazenyl)-N, N bis ((pyridin-2-yl) methyl) benzamine to form its copper complex has been reported by DFT methods. The theoretically predicted values for structural parameters are in agreement with the experimentally reported values. NMR chemical shifts calculated using B3LYP/DFT/GIAO level of theory gives information about binding of copper atom with three nitrogen atoms namely N (3, 8 and 11). Orbital overlap population analysis using DFT/B3LYP/SDD level of theory is used to study the kind of interactions involved in binding of copper with the three nitrogen atoms. DOS studies are done to know about the contribution of alpha, beta electrons to the valence and conduction band. IR spectroscopy investigations gave the absorption bands for the formation of title compound. Electronic spectrum along with HOMO-LUMO energies of the title compound has been investigated using Time-dependent (TD-DFT) approach.

Transfer Matrix Approach for Two-State Scattering Problem with Arbitrary Coupling

The present work deals with the calculation of transition probability between two diabatic potentials coupled by any arbitrary coupling. The method presented in this work is applicable to any type of coupling while for numerical calculations we have assumed the arbitrary coupling as Gaussian coupling. This arbitrary coupling is expressed as a collection of Dirac delta functions and by the use of the transfer matrix technique the transition probability from one diabatic potential to another diabatic potential is calculated. We examine our approach by considering the case of two constant potentials coupled by Gaussian coupling as an arbitrary coupling.

A DFT study of structural and electronic properties of Zn1−xSbxTe with x = (0.25,0.50,0.75)

In the present work, we report the structural and the electronic properties of the alloy Zn1−xSbxTe with x = (0.25%, 0.50% and 0.75%). Ab initio calculations are based upon the density functional theory with generalized gradient approximation and Perdew–Burke–Ernzerhof (PBE) exchange–correlation functional. In our calculations, we found that antimony (Sb) doping in zinc telluride (ZnTe) system introduces some bands which mainly originate from s- and p-states of Te and Sb atom and are primarily responsible for n-type and p-type conductivity.