Adaptive chaos synchronization of an attitude control of satellite: A backstepping based sliding mode approach.

This paper uses adaptive backstepping sliding mode control to synchronize two satellite attitude dynamics with perturbing torques. The external perturbing torques induce chaotic motion with no control inputs. The proposed control system uses Lyapunov theory and Barbalat's Lemma to guarantee the asymptotic stability of the controlled system. Simulation results confirm the effectiveness of the proposed design.

Harris hawks optimization algorithm for model order reduction of interconnected wind turbines.

This paper illustrates the investigation of higher-scale interconnected wind turbine to realize its analytical design and simulation performance in terms of reduced order model. The present research is aimed to visualize the efficacy of the propounded harris hawks optimization (HHO) approach for different reduced order transfer functions with reference to model order reduction studies. Compared to the higher-scale model, the applied methodology aims to obtain better results in terms of steadiness and computational effort. Moreover, to realize a higher-dimensional power system, the implementation of the HHO may proffer more effectiveness and robustness as opposed to the state-of-the-art optimization techniques. The applied methodology aims to obtain better results in terms of stability and computational effort. Furthermore, to realize a higher dimensional system, implementation of the HHO may offer more effectiveness and robustness as opposed to the state-of-the-art optimization techniques.

Two-Particle Interference with Double Twin-Atom Beams.

We demonstrate a source for correlated pairs of atoms characterized by two opposite momenta and two spatial modes forming a Bell state only involving external degrees of freedom. We characterize the state of the emitted atom beams by observing strong number squeezing up to -10 dB in the correlated two-particle modes of emission. We furthermore demonstrate genuine two-particle interference in the normalized second-order correlation function g^{(2)} relative to the emitted atoms.

Spectroscopic investigation of some electron withdrawing groups substituted TTF donor.

The structure optimization and spectroscopic properties for some derivatives of tetrathiafulvalene in both the neutral and ionized forms have been studied. The electron withdrawing groups like -CN, -CF3 and -CO2Me were considered to study the effect on structure, vibrational and electronic properties of tetrathiafulvalene. All the calculations were carried out at density functional theory incorporated with B3LYP exchange functional. The CAM-B3LYP exchange-correlation energy functional was also assessed for the determination of molecular structures. The normal coordinate analysis was performed to compute potential energy distributions of the normal modes which were used for the subsequent normal modes assignment. The temperature dependent Raman spectra have been presented showing the relative reduction in Raman intensity. The ionization of TTF-CN leads a very interesting effect. The IR spectrum of neutral TTF-CN contains a very strong CN stretching band at 2251 cm-1 while it is completely diminished in IR spectrum of TTF-CN cation. NBO analyses were also performed to study the electronic structure, second order perturbation and HOMO-LUMO and their energies. Some important thermodynamical parameters have been presented in which entropy calculation reveals below 50% contribution of vibrational motion in all the three molecules.

Conformational study of octopamine in gas phase and effect of hydrochloride.

This work deals with the molecular modeling and vibrational spectra of all the twenty conformers of an important biomolecule octopamine which have been investigated using the DFT/B3LYP level of theory in combination with the 6-31++g(d,p) as a suitable basis set. The experimental FTIR and FTRaman spectra of octopamine neurotransmitter were recorded in the spectral region 400-4000 cm-1 and 50-4000 cm-1 respectively and correlated with the calculated spectra of the most stable conformer. The effect of hydrochloride on the important geometrical parameters of most stable conformer of octopamine was also studied. The normal coordinate analysis was performed to scale the theoretical frequencies and to calculate potential energy distributions for precise normal mode assignment. Most of the frequencies were in good agreement with experimental one. However, some have been modified. Natural bond orbital analysis was performed in order to confirm the stability of electronic structure of octopamine molecule. HOMO-LUMO analysis for all the twenty conformers was also performed to give the transition profile and to study the chemical reactivity of octopamine.

Structural confirmation and spectroscopic study of a biomolecule: Norepinephrine.

The present work deals with the conformational and vibrational spectroscopic study of an important bio-molecule named norepinephrine in gas phase. The FTIR and FTRaman spectrum of norepinephrine in amorphous form were recorded in wavenumber range 4000-400 cm-1 and 4000-50 cm-1 respectively. We have investigated twenty-seven stable conformational structures of norepinephrine molecule. All the calculations have been done using Density Functional Theory with exchange functional B3LYP incorporated with the 6-31++G(d, p) basis set. The effect of hydrochloride on different bond lengths, bond angles and dihedral angles in the most stable conformer has also been studied. The total potential energy distribution for both the most stable conformer and the most stable conformer in hydrochloride was performed with the help Normal coordinate analysis method. Most of the calculated vibrational frequencies are in good agreement with the experimental frequencies. The natural bond orbital analysis was also performed to ensure the stability of electronic structures of norepinephrine. To know chemical reactivity of norepinephrine molecule we have calculated the energy gap between HOMO and LUMO orbitals and it has found above 5 eV in all the conformers.

Spectroscopic investigation of some building blocks of organic conductors: A comparative study.

Theoretical molecular structures and IR and Raman spectra of di and tetra methyl substituted tetrathiafulvalene and tetraselenafulvalene molecules have been studied. These molecules belong to the organic conductor family and are immensely used as building blocks of several organic conducting devices. The Hartree-Fock and density functional theory with exchange functional B3LYP have been employed for computational purpose. We have also performed normal coordinate analysis to scale the theoretical frequencies and to calculate potential energy distributions for the conspicuous assignments. The exciting frequency and temperature dependent Raman spectra have also presented. Optimization results reveal that the sulphur derivatives possess boat shape while selenium derivatives possess planner structures. Natural bond orbitals analysis has also been performed to study second order interaction between donors and acceptors and to compute molecular orbital occupancy and energy.

Conformational study of neutral histamine monomer and their vibrational spectra.

Molecular modeling and potential energy scanning of histamine molecule, which is an important neurotransmitter, with respect to the dihedral angle of methylamine side chain have done which prefer three different conformers of histamine monomer. We have calculated molecular structures and vibrational spectra with IR and Raman intensities of these conformers using Density Functional Theory (DFT) with the exchange functional B3LYP incorporated with the basis set 6-31++G(d,p) and Hartree-Fock (HF) with the same basis set. We have also employed normal coordinate analysis (NCA) to scale the theoretical frequencies and to calculate potential energy distributions (PEDs) for the conspicuous assignments. Normal modes assignments of some of the vibrational frequencies of all the three conformers are in good agreement with the earlier reported experimental frequencies of histamine whereas others have modified. The standard deviations between the theoretical and experimental frequencies fall in the region 13-20cm(-1) for the three conformers. NBO analyses of histamine conformers were also performed. The net charge transfers from ethylamine side chain to the imidazole ring. The intensive interactions between bonding and anti-bonding orbitals are found in imidazole ring. The HOMO-LUMO energy gap is nearly 5.50eV.

Speed and efficiency limits of multilevel incoherent heat engines.

We present a comprehensive theory of heat engines (HE) based on a quantum-mechanical "working fluid" (WF) with periodically modulated energy levels. The theory is valid for any periodicity of driving Hamiltonians that commute with themselves at all times and do not induce coherence in the WF. Continuous and stroke cycles arise in opposite limits of this theory, which encompasses hitherto unfamiliar cycle forms, dubbed here hybrid cycles. The theory allows us to discover the speed, power, and efficiency limits attainable by incoherently operating multilevel HE depending on the cycle form and the dynamical regimes.

Molecular modeling, spectroscopic signature and NBO analysis of some building blocks of organic conductors.

Vibrational spectra with IR and Raman intensities in optimum state have been calculated for 2,2'-Bi-1,3-diselenole (commonly known as tetraselenafulvalene) and its halogen derivatives. All these calculations have been done by employing density functional theory (DFT) and second order Moller-Plesset perturbation theory (MP2) methods incorporated with suitable functionals and basis sets. Normal coordinate analysis has also been performed to calculate potential energy distributions (PEDs) to make a conspicuous assignment. The vibrational frequencies of all the four molecules have been assigned using PEDs and the results are compared with available values for the most similar molecules like tetrathiafulvalene. The molecular stability and bond strength have investigated by applying the Natural Bond Orbital (NBO) analysis. The energy gap between HOMO and LUMO is 2.041 eV for tetraselenafulvalene and it is slightly less than 2eV for halogen derivatives which implies that these molecules fall in the wide band gap semiconductor groups.

Theoretical vibrational spectra and thermodynamics of organic semiconductive tetrathiafulvalene and its cation radical.

Molecular structure in optimum geometry and vibrational frequencies of pentafulvalene [bicyclopentyliden-2,4,2',4'-tetraene], tetrathiafulvalene [2,2'-bis(1,3-dithiolylidene)] and its cation are calculated. All the calculations are carried out by employing density functional theory incorporated with a suitable basis set. Normal coordinate analysis is also employed to scale the DFT calculated frequencies and to calculate potential energy distributions. The molecular structures and vibrational frequencies are compared for both the pentafulvalene and tetrathiafulvalene molecules. The effect upon geometry and vibrational frequencies of TTF due to charge transfer has also been studied. The vibrational partition function and hence, the thermodynamical properties, such as Helmholtz free energy, entropy, specific heat at constant volume and enthalpy are also calculated and compared for the title molecules. The reason of conductivity of tetrathiafulvalene has been tried to explain on the basis of molecular geometry and normal modes. Study of vibrational partition function exhibits that below 109 K, PFV starts to condense.

Theoretical DFT study on spectroscopic signature and molecular dynamics of neurotransmitter and effect of hydrogen removal.

Vibrational spectroscopic study has been made for the serotonin molecule and its deprotonated form. The Infrared and Raman spectra in optimum geometry of these two molecules are calculated using density functional theorem and the normal modes are assigned using potential energy distributions (PEDs) which are calculated using normal coordinate analysis method. The vibrational frequencies of these two molecules are reported and a comparison has been made. The effect of removal of the hydrogen atom from the serotonin molecule upon its geometry and vibrational frequencies are studied. Electronic structures of these two molecules are also studied using natural bond orbital (NBO) analysis. Theoretical Raman spectrum of serotonin at different exciting laser frequencies and at different temperatures are obtained and the results are discussed. Present study reveals that some wrong assignments had been made for serotonin molecule in earlier study.

Vibrational fundamentals and natural bond orbitals analysis of some tri-fluorinated benzonitriles in ground state.

The theoretical IR and Raman spectra of the 2,3,4-, 2,3,6-, 2,4,5- and 3,4,5-tri-fluorobenzonitrile molecules have been calculated by using the density functional method in the ground state. The rigorous normal coordinate analyses based upon both an empirical force field and quantum chemical calculations have been performed and the detailed vibrational assignment has been made on the basis of the calculated potential energy distributions (PEDs). A comparison of molecular geometries, atomic charges and vibrational fundamentals of these molecules has been reported. The effects of fluorination upon the geometries, atomic charges and vibrational frequencies of benzonitrile have been discussed. Several ambiguities and contradictions in the previously reported vibrational assignments have been clarified. In addition, the variation of Raman intensity with excitation frequency and with temperature has also been studied.

FTIR and Raman spectra and optimized geometry of 2,3,6-tri-fluorobenzoic acid dimer: a DFT and SQMFF study.

Raman and FTIR spectra of the 2,3,6-tri-fluorobenzoic acid molecule have been recorded in the regions 50-4000cm⁻¹ and 400-4000cm⁻¹, respectively. Vibrational frequencies have been calculated by employing DFT method in dimeric form in optimum state. SQM force field has also been used to calculate potential energy distributions in order to make conspicuous vibrational assignments. Raman activities calculated by DFT method have been converted to the corresponding Raman intensities using Raman scattering theory. Optimized bond lengths and angles of the title molecule have been interpreted and compared with the earlier reported experimental values for benzoic acid and some mono and di-fluorinated benzoic acids. Some of the vibrational frequencies of the title molecule are effected upon profusely with the fluorine substitutions in comparison to benzoic acid and these differences have been interpreted. The strong doubly hydrogen-bonded interface of the dimerized system is well demonstrated by the red shift in OH stretching frequency concomitant with the elongation of bond length.

Experimental and calculation aspects of vibrational spectra and optimized geometry of 2,3,4-tri-fluoro-benzoic acid dimer.

Raman and FTIR spectra for 2,3,4-tri-fluoro-benzoic acid molecules have been recorded in the regions 50-4000 cm(-1) and 400-4000 cm(-1) respectively. The geometrical parameters have been optimized in both the monomeric and dimeric forms while vibrational frequencies have been calculated in optimum state in the dimeric form by employing DFT method. SQM force fields have also been used to calculate potential energy distributions in order to make conspicuous vibrational assignments. Raman activities calculated by DFT method have been converted to the corresponding Raman intensities using Raman scattering theory. Optimized geometries of the molecule have been interpreted and compared with the earlier reported experimental values for benzoic acid and some mono and di-fluorinated benzoic acids. Some of the vibrational frequencies of the title molecule are effected upon profusely with the fluorine substitutions in comparison to benzoic acid and these differences have been interpreted. The strong doubly hydrogen-bonded interface of the dimerized system is well demonstrated by the red shift in OH stretching frequency concomitant with the elongation of bond length.

FTIR and Raman spectra, DFT and normal coordinate computations of 2,4,5- and 2,4,6-tri-fluoroanilines.

FTIR and Raman spectra of the 2,4,5- and 2,4,6-tri-fluoroaniline molecules have been reported. Density functional method has been employed to calculate the optimized geometrical parameters, atomic charges and vibrational frequencies. In addition, SQM force field method has also been employed to calculate potential energy distribution matrix. The observed and calculated IR and Raman spectra have been simulated. Each normal mode has been assigned using observed and calculated vibrational frequencies, IR and Raman intensities, depolarization ratios for the Raman lines, vector displacements and potential energy distributions. Optimized geometrical parameters, atomic charges and vibrational frequencies have been compared for the title molecules. The influences of presence of fluorine atoms to the geometries and normal modes of the aniline molecule have also been discussed.

FTIR and Raman spectra and SQM force field calculation for vibrational analysis of 2,3,4- and 2,3,6-tri-fluoro-anilines.

Raman and FTIR spectra for 2,3,4- and 2,3,6-tri-fluoro-aniline molecules have been recorded in the wavenumber regions 50-4000 and 400-4000 cm(-1) respectively. Measurement of depolarization ratios for the Raman lines for both the molecules has also been made. The HF with the basis set 6-31++G(d,p) and DFT with the basis sets 6-31++G(d,p) and 6-311++G(d,p) have been employed to carry out the molecular geometries, atomic charges and vibrational frequencies along with their IR and Raman intensities. Normal coordinate analysis method has also been employed to carry out the potential energy distributions (PEDs). The assignment of each normal mode has been made using observed and calculated frequencies, their IR and Raman intensities, depolarization ratios for the Raman lines and PEDs. The influences of fluorine atoms towards the geometries and normal modes of the aniline molecule have been discussed.

Quantum chemical determination of molecular geometries and interpretation of FTIR and Raman spectra for 2,4,5- and 3,4,5-tri-fluoro-benzonitriles.

Raman and FTIR spectra of 2,4,5- and 3,4,5-tri-fluoro-benzonitriles have been recorded in the regions 50-4000 cm(-1) and 400-4000 cm(-1), respectively. Measurement of depolarization ratios for the Raman lines has also been made. Optimized geometrical parameters, charge distributions and vibrational wavenumbers were calculated using ab initio quantum chemical Gaussian 03, Revision C.02 software. Each vibration has been assigned using observed wavenumbers in the IR and Raman spectra and their relative intensities which measured by normalizing the highest intensity, depolarization ratios of the Raman lines, the calculated frequencies and vector displacements with the help of GaussView software.

Force field calculations and reassigments of Raman and IR frequencies of pyrazine-N,N'-dioxide.

Force field calculations have been carried out for the planar and non-planar modes of pyrazine-N,N'-O2 using the observed vibrational frequencies obtained from the IR and Raman spectral studies on pyrazine-N,N'-O2-h4 and pyrazine-N,N'-O2-d4 reported in the literature [D.A. Thornton, P.F.M. Verhoeven, G.M. Watkins, Herman O. Desseyn, Benjamin J. Van der Veken, Spectrochim. Acta 46A (1990) 1439]. The purpose of the present work is to determine force fields for the pyrazine-N,N'-O2 molecule and to present vibrational assignments for the observed IR and Raman frequencies to the fundamental modes, combination bands and overtones. The planar force field determined in the present case is expected to be better than that reported earlier [S. Szöke, G. Varsanyi, E. Baitz, Acta Chim. 53 (1967) 345] because of the inclusion of the observed frequencies due to pyrazine-N,N'-O2-d4 isotopomer. In addition, the non-planar force field for this molecule is reported for the first time.