Journal of Computational Methods in Sciences and Engineering - Volume 10, issue 3-6

Authors: Chernov, V.E. | Zon, B.A.

Article Type: Research Article

Abstract: Due to nonlinear rotation of polarization, the stochastic intensity and the spatio-temporal inhomogeneity of a multimode laser beam results to its depolarization when propagating in a nonlinear media. The ensemble and spatio-temporal averaging of Stokes parameters was performed analytically for an isotropic media and numerically for an anisotropic one. The experimentally measurable Stokes parameters show monotonic or oscillating decreasing dependence on the propagation distance; the characteristic depolarization length is evaluated. With respect to depolarization the anisotropic media is shown to behave like the isotropic one if the radiation intensity is sufficiently high. The measured value of depolarization agrees with the …presented calculations. Show more

Keywords: Multimode laser pulse, nonlinear self-rotation of polarization ellipse

DOI: 10.3233/JCM-2010-0348

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 10, no. 3-6, pp. 183-195, 2010

Authors: Déjardin, Jean-Louis

Article Type: Research Article

Abstract: Anomalous diffusion is considered in the context of fractional dynamics applied to dielectric relaxation of polyelectrolyte solutions. The approach starts from a fractional Smoluchowski equation in configuration space of molecular orientations of macroions and displacements of couterions. By using a perturbation procedure, we derive analytic expressions for the buildup and reversing field processes of the electric polarization given by the expectation value of the product of the first Legendre polynomial by the first Hermite polynomial. The first harmonic component of the ac dielectric response is also calculated. All these results are illustrated by plots demonstrating the effect of both the …coupling (rotation-translation) parameter a and the critical exponent α (subdiffusion). Show more

DOI: 10.3233/JCM-2010-0321

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 10, no. 3-6, pp. 197-202, 2010

Authors: Jissy, A.K. | Datta, Ayan

Article Type: Research Article

Abstract: DFT and NMR calculations performed on isophlorin (1) and their derivatives (2–10) show that the 4O and the trans 2O, 2S derivatives (2 and 5) are anti-aromatic. The presence of strong S … S p π - p π bonding interactions stabilizes the planar structure (5) compared to the non-planar cis-isomer (8). Isophlorins are predicted to have very low electron reorganization energies (λ electron ∼ 0.10 eV ) which remain unaffected by puckering through steric interactions or solvation in aqueous media. We …predict isophlorins to be the ideal candidates for n-Channel organic conductors. Show more

DOI: 10.3233/JCM-2010-0319

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 10, no. 3-6, pp. 203-218, 2010

Authors: Brennand, R.A. | de A. Machado, A.E.

Article Type: Research Article

Abstract: The modelling of the diethynylsilane derivatives reveals large magnitudes of the first hyperpolarizability (β). The electron donor (D) and acceptor (A) groups are attached at both ends of the oligomers that containing up to ten heterocyclic rings. Several D/A pairs with different strengths were tested in this investigation. The magnitude of static and dynamic β was computed using the AM1/TDHF methodology. The presence of the alkyl donor groups containing heteroatom in the oligomers investigated contributes most for the largest values of the β hyperpolarizability observed. The effect of the oligomer chain length on the β magnitude is also investigated. The …results demonstrate that the diethynylsilane derivatives are promising as second-order nonlinear optical materials. Show more

Keywords: β Hyperpolarizabilty, AM1/TDHF methodology, diethynylsilane oligomers

DOI: 10.3233/JCM-2010-0335

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 10, no. 3-6, pp. 219-226, 2010

Authors: De Dominicis, L.

Article Type: Research Article

Abstract: The process of Sum Frequency Generation (SFG) in chiral Carbon Nanotubes (CNTs), with the exciting laser beams propagating along the CNT symmetry axis, is here investigated. First the general form of the first hyperpolarizability third rank tensor β for chiral CNTs is determined with group projector technique method applied to the Lnp 22 line group describing their symmetry. For this purpose, the group natural factorization has been adopted and the associated irreducible representations, parameterized in terms of helical quantum numbers, then used to construct the group projector operator in the relevant vector space. The method demonstrates that second harmonic generation …is symmetry forbidden in the collinear geometry while, conversely, SFG is symmetry allowed. Subsequently, the SFG far-field radiation pattern has been modelled with a calculation scheme derived from antenna's theory and already used for simulation of Rayleigh scattering from a CNT. The method has been overhauled for describing the here considered nonlinear optical interaction. The study of the role played by two induced counter-propagating current density retarded waves in shaping the radiation pattern is addressed and simulations are reported in the limit regimes of strong and weak attenuation. Show more

Keywords: Carbon nanotubes, line groups, first hyperpolarizability, sum frequency generation

DOI: 10.3233/JCM-2010-0320

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 10, no. 3-6, pp. 227-237, 2010

Authors: Paschoal, Diego | Costa, Marcello F. | Junqueira, Georgia M.A. | Dos Santos, Hélio F.

Article Type: Research Article

Abstract: In this paper, basis sets for H, C, N and O atoms were adjusted to obtain electric properties of diatomic molecules. The dipole moment, polarizability and first-order hyperpolarizability were calculated for H2 , CH+ , CN- and CO molecules and the basis sets modified to reproduce the reference data available. A sequential methodology was used, where the basis set for H is firstly adjusted and then used to fit the basis set for C in the CH+ molecule and so on. The final basis sets were (7s2p1d)→[3s2p1d] for H and (9s5p2d)→[5s3p2d] for C and O. In the case …of N atom, the best basis set was found to be (9s5p1d)→[5s3p1d], where only one set of d polarization functions was needed. The atomic basis sets fitted were further utilized for calculation of geometry and electric properties of 36 benzene derivatives mono- and di-substituted by electron donor and acceptor groups attached at ortho, meta and para positions. The results were satisfactory for most of molecules. For instance, in the case of p-nitroaniline, an important push-pull benzene derivative, the first hyperpolarizability was predicted to be 9.4 × 10-30 e.s.u. in excellent agreement with experimental value, 9.2 × 10-30 e.s.u.. Besides electric properties, our basis sets also gave good geometries for polyatomic molecules at reasonable computational cost. Therefore, the results reported in the present paper suggest the use of our modified basis sets for calculation of geometry and electric properties (linear and non-linear) of push-pull benzene derivatives like molecules. Show more

Keywords: ab initio, electrical properties, Gaussian basis set, hyperpolarizability, NLO

DOI: 10.3233/JCM-2010-0343

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 10, no. 3-6, pp. 239-256, 2010

Authors: El-Kader, M.S.A.

Article Type: Research Article

Abstract: The contribution of the quadrupole polarizability C to the long-range polarizability of two interacting rare-gas atoms and methane molecules is specified by fitting the trace and anisotropy models to the intensity of the isotropic and anisotropic interaction-induced light scattering spectra. Good agreement with ab initio results in the literature is obtained and the first few even moments of these profiles are in excellent agreement with experiments.

Keywords: Quadrupole polarizabilities/rare-gas/CH4

DOI: 10.3233/JCM-2010-0322

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 10, no. 3-6, pp. 257-263, 2010

Authors: Ficek, Zbigniew | Tanaś, Ryszard

Article Type: Research Article

Abstract: We discuss a simple model for creation of entanglement in a system composed of two two-level atoms interacting with a common environment. The role of the environment in entangling and disentangling of the atoms is explored. We demonstrate how the spontaneous decay of an initial excitation of the system can create a transient entanglement between the atoms. The opposite situation is also discussed where a spontaneous disentanglement of initially entangled atoms may exhibit some unusual features such as entanglement sudden birth, the phenomenon of entanglement sudden death and revival of entanglement. We provide a discussion of these unusual phenomena in …terms of the density matrix elements of the system and show the connection of the phenomena with the threshold behaviour of the concurrence. Show more

DOI: 10.3233/JCM-2010-0323

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 10, no. 3-6, pp. 265-289, 2010

Authors: Fisz, Jacek J. | Buczkowski, Marcin | Rożnowska, Anna | Miszta, Przemysław

Article Type: Research Article

Abstract: We here discuss a problem of time-resolved fluorescence polarization spectroscopy at two-photon excitations of macroscopically isotropic molecular media, that can be organized locally on a nano-scale. The simplifying assumptions on the hydrodynamical shape of fluorophores and on the form of the two-photon absorption tensor, are considered and displayed on the corresponding examples of the emission anisotropy synthetic decays. These assumptions reduce the number of the model parameters making the theoretical description of the discussed spectroscopic technique applicable in the experimental practice. Because the two-photon excitations of fluorescence require the application of the exciting light of appropriately high intensity, and that …may have a negative influence on the quality of the experimental data collected, we discuss the application of the wide-angular detection-aperture technique in such experiments. Furthermore, we consider the application of the symmetry adapted callibration (SAC) method enabling one to accurately analyze the experimental data even if the collecting optics employed is not ideal and is affected by several unexpected technical imperfections that are hard to be accounted for analytically. Show more

Keywords: Two-photon excitation, fluorescence depolarization, intermolecular interactions, rotational dynamics, order parameters, membrane vesicles, labeled macromolecules, solutions

DOI: 10.3233/JCM-2010-0324

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 10, no. 3-6, pp. 291-319, 2010

Authors: Galashev, A.Y.

Article Type: Research Article

Abstract: The absorption and scattering of IR radiation by aqueous ultradisperse systems that absorb nitrogen, oxygen, or argon are studied with the molecular dynamics method on the basis of a flexible molecule model. After nitrogen or argon is captured by an aqueous disperse system, the absorption of the IR radiation by this system increases owing to the enhancement of intramolecular vibrations. It is demonstrated that the integral intensity of absorption of IR radiation decays after water clusters adsorb oxygen. As the nitrogen concentration in a system of water clusters rises, the power of IR radiation emitted by the system increases significantly. …The attachment of molecular oxygen by clusters leads to decay of the power of their IR radiation, while the capture of atomic oxygen, on the contrary, is accompanied by an increase in the rate of dissipation of energy accumulated by water aggregates. The power of radiation generated by cluster systems at the expense of thermal energy increases considerably when there is one adsorbed argon atom per cluster and decreases with a twofold increase in the number of argon atoms in clusters. Show more

Keywords: Absorption, infra-red spectra, argon, nitrogen, oxygen, power of radiation, water clusters

DOI: 10.3233/JCM-2010-0326

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 10, no. 3-6, pp. 321-340, 2010

Authors: Alexiewicz, Wladyslaw | Grygiel, Krzysztof

Article Type: Research Article

Abstract: Assuming the low molecular reorientation approximation, the formulae for linear electric polarization induced in liquids composed of rigid, noninteracting, dipolar and asymmetric-top molecules in spherical solvents were derived. The Kalmykov's equation [Phys.Rev., E 65 (021101) 2001] – equivalent to the classical, noninertial Smoluchowski-Debye model of rotational diffusion was applied. In order to highlight the influence of the anisotropy of rotational diffusion tensor components and the orientation of permanent dipole moment of the molecule on the complex linear electric susceptibility, we present three-dimensional plots of the dispersion and absorption spectra, Cole-Cole diagrams for different values of the anisotropies of rotational diffusion …tensor components and different frequencies of an ac electric field. Show more

DOI: 10.3233/JCM-2010-0311

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 10, no. 3-6, pp. 341-356, 2010

Authors: Wang, Bing-Qiang | Wang, Fang-Fang | Ma, Fang | Li, Zhi-Ru | Wu, Di | Xu, Hong-Liang | Gu, Feng Long

Article Type: Research Article

Abstract: Recently, a novel type of intermolecular covalent interaction has been found in dimers with π-radical(s). In this paper, the optimized structure of the tetrathiafulvalence radical-cation dimer (TTF·+ –TTF·+ ) is obtained with all-real frequencies, in which a 20-center-2-electron intermolecular covalent π/π bonding with a double-tube shape is theoretically predicted. The covalent π/π bonding energy is estimated to be about -21 kcal·mol-1 which counteracts partly the Coulombic repulsion between two TTF·+ cations. This intermolecular covalent bonding can also influence the structure of the TTF·+ subunit, i.e., its molecular plane is bent by an angle θ=5.6°. In addition, adding …the background charges based on the TTF-TCNQ crystal structure, the interaction energy of TTF·+ –TTF·+ changes from a positive value to a large negative value. This work indicates that the TTF-TCNQ crystal structure built up from parallel, segregated stacks of cation radicals TTF·+ and anions TCNQ·- is stabilized by two main factors: the intermolecular covalent π/π bonding interaction between like-charged radicals and the effect of counterions. Show more

DOI: 10.3233/JCM-2010-0334

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 10, no. 3-6, pp. 357-366, 2010

Authors: Li, Xiaoping | Harrison, James F. | Gustafsson, Magnus | Frommhold, Lothar | Hunt, Katharine L. C.

Article Type: Research Article

Abstract: In earlier work, Li, Ahuja, Harrison, and Hunt have calculated the collision-induced polarizability Δα of a pair of hydrogen molecules at CCSD(T) level with an aug-cc-pV5Z basis, for 178 relative orientations of the pair, with the bond length in each molecule fixed at r=1.449 a.u. Here we present new results from an expansion of the second-rank tensor components of Δα as series in the spherical harmonics of the molecular orientation angles and the orientation angles of the intermolecular vector. The coefficients in this expansion depend on the separation R between the molecules. We compare the ab initio coefficients with predictions …from long-range perturbation theory, including the dipole-induced-dipole interactions at first and second order, higher-multipole induction, effects of nonuniform local fields, hyperpolarization, and van der Waals dispersion. Li and Hunt have derived equations for the long-range coefficients complete to order R-6 , using spherical-tensor methods developed by Bancewicz, Głaz, and Kielich for collision-induced light scattering by centrosymmetric linear molecules. We also give new results here for the van der Waals dispersion terms in both isotropic and anisotropic polarizability coefficients. We have calculated these coefficients by 64-point Gauss-Legendre quadrature, using the H2 polarizabilities and hyperpolarizabilities at imaginary frequencies computed by Bishop and Pipin, with explicitly correlated wave functions for isolated H2 molecules. We show that the ab initio values for the larger anisotropic polarizability coefficients converge to the predictions of the long-range theory, as the separation R between the molecules increases. The coefficients computed ab initio have been used by Gustafsson, Frommhold, Li, and Hunt to calculate the depolarized collision-induced roto-translational Raman spectra of hydrogen gas at 36 K and 50 K out to 800 cm-1 , and at 296 K out to 300 cm-1 . The general features of the experimental spectra are well reproduced, although the calculated intensities are ∼30% too large over much of the frequency range. Show more

Keywords: Collision-induced light scattering, depolarized Raman spectra, ab initio pair polarizabilities

DOI: 10.3233/JCM-2010-0328

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 10, no. 3-6, pp. 367-399, 2010

Authors: Karpov, V.B. | Korobkin, V.V.

Article Type: Research Article

Abstract: Some of the experimental measurements of the frequency shift and phase-conjugation fidelity gained from previous studies of stimulated scattering (SS) of nanosecond (5 ÷ 10 ns) near-ultraviolet (uv) (λ = 193 ÷ 351 nm) laser pulses in liquids (hexane, heptane, and others) are found to disagree with the theory of SS, which takes into account only the linear (single-photon) light absorption. To resolve the inconsistency, SS of XeCl excimer laser radiation (λ = 308 nm) with the duration of 8 ns in liquid hexane is investigated experimentally. A theoretical analysis of the results obtained revealed three nonlinear optical phenomena induced …by the heating due to two-photon absorption: stimulated thermal scattering (two-photon STS-2), phase mismatch for stimulated Brillouin scattering (SBS), and phase self-modulation. The experimental SS spectrum contains two additional lines – a two-photon STS-2 line and a genuine SBS line in the near-uv region. Show more

DOI: 10.3233/JCM-2010-0329

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 10, no. 3-6, pp. 401-423, 2010

Authors: Karpov, V.B. | Korobkin, V.V.

Article Type: Research Article

Abstract: The effects of linear (single-photon) and two-photon heating to the thin structures of the stokes and anti-stokes spectral components of stimulated Brillouin scattering (SBS) and stimulated temperature scattering (STS) are compared. The thin structures of the linear and two-photon STS-2 possess the same shapes. For the Fabry-Perot etalon based spectrum analyzer the linear and two-photon STS-2 components are experimentally indistinguishable not only from one another, but also from the STS-1 component. To reach the higher spectral resolution methods of heterodyning and intensity fluctuations correlation should be used. In contrast to a linear (single-photon) case for two-photon heating a stokes SBS …component exhibits the spectral shift depending on the pump intensity. Emergence of the anti-stokes SBS component is possible when the pump intensity is sufficiently high so that the positive two-photon thermal gain may compensate the negative electrostrictive gain. Show more

DOI: 10.3233/JCM-2010-0330

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 10, no. 3-6, pp. 425-437, 2010

Authors: Kowalewska-Kudłaszyk, A. | Leoński, W.

Article Type: Research Article

Abstract: We consider time-evolution of the disentanglement process of once generated entangled qubit pair as a result of the phase variation of the pumping field. As a source of maximally entangled states we use the nonlinear coupler (two oscillators with Kerr-like nonlinearities) with nonlinear internal interactions. The coupler prepared in a maximally entangled state interacts afterwards with external reservoir of thermal character and pumping field as well. We show that the fact of the coupling with additional state (which can create additional entanglement with one of the 2-qubit system's previously entangled states) is an origin of interesting entanglement decay behaviour. We …can observe shortening of both: entanglement death-time and entanglement birth caused by changing the phase of an external driving field. Show more

DOI: 10.3233/JCM-2010-0331

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 10, no. 3-6, pp. 439-445, 2010

Authors: Lamère, Jean François | Peyrou, Viviane | Sasaki, Isabelle | Lacroix, Pascal G. | Vendier, Laure | Boillot, Marie Laure

Article Type: Research Article

Abstract: Two complexes of formula [FeIII (salten)(DEAS)](BPh4 ) and [FeIII (salten)(MPS)](BPh4 ) are reported in which H2 salten is the 4-azaheptamethylene-1,7-bis(salicylideneiminate) quinquadentate Schiff base ligand, DEAS is 4'-diethylamino-stilbazole, and MPS is 4'-[2-(methoxymethyl)pyrrolidinyl]-stilbazole. Both complexes exhibit a partial S=5/2 → 1/2 spin crossover behaviour on cooling down to low temperature. Additionally, DEAS exhibits potential nonlinear optical (NLO) properties in relation to an intense π-π* charge transfer transition between the amine and the pyridine moieties. The temperature dependence of the optical spectra of [FeIII (salten)(DEAS)]+ is compared to that of 4'-diethylamino-1-methylstilbazolium (DEAMS+ ), a cation related to [FeIII (salten)(DEAS)]+ , in …which the NLO active DEAS ligand is linked to a methyl instead of an iron complex, and therefore exhibits no magnetic behaviour. The occurrence of a red shift upon cooling down is discussed in relation with the spin equilibrium, on the basis of the ZINDO calculated spectra. A similar shift is observed between [FeIII (salten)(mepepy)]+ complex (mepepy=1-(pyridin-4-yl)-2-(N-methylpyrrol-2-yl)-ethane) and Me-mepepy+ , N-methylated form of mepepy. The potential effect of these behaviours on the NLO properties is discussed, in a perspective of molecular materials with interacting electronic capabilities. Show more

Keywords: Spin crossover, nonlinear optics, ZINDO, semi-empirical methods, UV-vis spectra

DOI: 10.3233/JCM-2010-0332

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 10, no. 3-6, pp. 447-463, 2010

Authors: Long, V. Cao | Leoński, W. | Viet, H. Nguyen

Article Type: Research Article

Abstract: We consider the propagation of optical pulses in Kerr medium in the presence of a harmonic potential for 2D case in framework of Variational Approximation (VA). We will use two types of trial function: gaussian and hyperbolic secant ones. We will show that if the value of the nonlinearity parameter reaches a certain critical value the pulse collapses. This collapse corresponds to the physical situation when the self-focusing effect dominates over the dispersion and diffraction. We show that our analytical results are confirmed by several numerical calculations which are in excellent agreement with those of the VA predictions. By the …analogy between the propagation equation and Gross-Pitajevski equation for Bose-Einstein condensates (BECs) we can transfer obtained results to the case of BEC placed in a external harmonic potential. It follows that in both of cases the wave collapse can appear. Show more

DOI: 10.3233/JCM-2010-0333

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 10, no. 3-6, pp. 465-472, 2010

Authors: Makowski, Marcin | Gu, Feng Long | Aoki, Yuriko

Article Type: Research Article

Abstract: The elongation methodology is extended towards description of excited states through the ab initio CIS expansions in regionally localized molecular orbital basis. The formalism and implementation of the elongation-CIS method are presented. The expected accuracy of the method in comparison to the conventional CIS approach is illustrated by the results of calculations for model systems.

Keywords: Elongation method, excited states, configuration interaction

DOI: 10.3233/JCM-2010-0312

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 10, no. 3-6, pp. 473-481, 2010

Authors: Mestechkin, M. M.

Article Type: Research Article

Abstract: The explicit expression for magnetic induction vector of a ring current at arbitrary point in toroidal coordinates is presented in terms of the full elliptic integral of the first kind and its derivative over integral modulus. There is a conjugated point for any observation point: it is an image of the latter in a sphere with the ring current as its equator. The conjugated point lies on the same vector and has the same integral modulus as the initial point.

Keywords: Ring current, magnetic induction vector, full elliptic integral, toroidal coordinates

DOI: 10.3233/JCM-2010-0336

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 10, no. 3-6, pp. 483-488, 2010

Authors: Mikkelsen, Kurt V.

Article Type: Research Article

Abstract: Homogeneous dielectric media models are considered when calculating nonlinaer optical molecular porperties using correlated electronic structure response methods.

Keywords: Homogeneous dielectric media, correlated electronic structure, response methods, nonlinear optical properties

DOI: 10.3233/JCM-2010-0337

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 10, no. 3-6, pp. 489-499, 2010

Authors: Miranowicz, Adam | Horst, Bohdan | Koper, Andrzej

Article Type: Research Article

Abstract: We review some counterintuitive properties of standard measures describing quantum entanglement and violation of Bell's inequality (often referred to as “nonlocality”) in two-qubit systems. By comparing the nonlocality, negativity, concurrence, and relative entropy of entanglement, we show: (i) ambiguity in ordering states with the entanglement measures, (ii) ambiguity of robustness of entanglement in lossy systems and (iii) existence of two-qubit mixed states more entangled than pure states having the same negativity or nonlocality. To support our conclusions, we performed a Monte Carlo simulation of 106 two-qubit states and calculated all the entanglement measures for them. Our demonstration of the …relativity of entanglement measures implies also how desirable is to properly use an operationally-defined entanglement measure rather than to apply formally-defined standard measures. In fact, the problem of estimating the degree of entanglement of a bipartite system cannot be analyzed separately from the measurement process that changes the system and from the intended application of the generated entanglement. Show more

DOI: 10.3233/JCM-2010-0338

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 10, no. 3-6, pp. 501-512, 2010

Authors: Moussi, Sofiane | Ouamerali, Ourida

Article Type: Research Article

Abstract: The ONIOM method was used to reproduce geometrical parameters, atomic charges, dipole moment for α and β L-Fucopyranose which are biological interest molecules. The results of ONIOM(MP2/HF) and ONIOM(B3LYP/HF) calculations were compared to the values obtained by means of its corresponding theoretical levels MP2, DFT and RHF with 6-31G* bases set, using GAUSSIAN 98 software.

DOI: 10.3233/JCM-2010-0339

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 10, no. 3-6, pp. 513-533, 2010

Authors: Roset, Lurdes | Perez, Juan J.

Article Type: Research Article

Abstract: In the present report we analyze the performance of DFT to compute molecular polarizabilities through the analysis of molecular polarization potential that can be used as a tool to understand their spatial effects in the calculation of molecular polarizabilities. This is done in the present report through the results obtained for three reference molecules: hydrogen cyanide, formaldehyde and urea. Calculations were carried out at the density functional theory using the BLYP and B3LYP functionals. The results of the polarization maps reveal similar trends observed with the calculation of the different components of the polarizability tensor. However, the use of the …maps permits to understand spatial effects specific for each level of calculation and each basis set. Show more

DOI: 10.3233/JCM-2010-0340

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 10, no. 3-6, pp. 535-543, 2010

Authors: Rau, I. | Krupka, O. | Grote, J.G. | Kajzar, F. | Sahraoui, B.

Article Type: Research Article

Abstract: Third-order nonlinear optical properties of functionalized deoxyribonucleic acid (DNA) are studied by optical third harmonic generation at 1 0642 nm fundamental wavelength. The studies were performed on thin films of DNA-CTMA and DNA-CTMA doped with a charge transfer molecules DR1 and with a cobalt phthalocyanine. They show that DNA, similarly as synthetic polymers, can be used as matrix for highly active NLO chromophores.

Keywords: DNA, DNA-CTMA, doped DNA-CTMA, third harmonic generation, NLO susceptibility

DOI: 10.3233/JCM-2010-0341

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 10, no. 3-6, pp. 545-557, 2010

Authors: Salam, A.

Article Type: Research Article

Abstract: Within the framework of molecular quantum electrodynamics, the method of induced multipole moments is used to compute the laser-induced intermolecular energy shift between an electric dipole polarizable molecule and a magnetic dipole susceptible molecule, and between two magnetic dipole polarizable molecules. The physical viewpoint adopted in the calculation is one in which an applied electromagnetic field induces molecular multipole moments in each entity, which couple via the retarded resonant multipole-multipole interaction tensors. Expectation values taken over the ground electronic states of the material system, and a radiation field state containing n photons, leads directly to the coupling energy. Results are …obtained for external radiation in a fixed orientation relative to the internuclear axis, with a thorough polarization analysis being carried out for linearly and circularly polarized radiation propagating in directions parallel and perpendicular to the separation distance vector, as well as for a freely tumbling molecular pair. Comparison is made with field-induced discriminatory energy shifts occurring between optically active molecules – which also involve coupling of electric and magnetic dipole moments, and the leading contribution to optical binding forces arising within the electric dipole approximation. Show more

DOI: 10.3233/JCM-2010-0342

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 10, no. 3-6, pp. 559-567, 2010

Authors: Slanina, Zdeněk | Uhlík, Filip | Lee, Shyi-Long | Nagase, Shigeru

Article Type: Research Article

Abstract: The paper reports computations for Al@C82 , Sc@C82 , Y@C82 and La@C82 based on encapsulation into the IPR (isolated pentagon rule) C2v C82 cage. Their structural and bonding features are also used for evaluations of the relative production yields, employing the encapsulation Gibbs-energy terms and saturated metal pressures. The results can be well related to the ionization potentials of the free metal atoms.

DOI: 10.3233/JCM-2010-0344

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 10, no. 3-6, pp. 569-574, 2010

Authors: Ratajczak, Blazej | Sliwinska-Bartkowiak, Malgorzata | Koziol, Tomasz | Coasne, Benoit | Gubbins, Keith E.

Article Type: Research Article

Abstract: We report an experimental and simulation study of binary mixtures of o- and m-nitrotoluene with decane and hexadecane. Mixtures of o-nitrotoluene with alkanes form a classical critical mixtures, but m-nitrotoluene / n – alkane mixtures show an apparent critical point, which lies in a metastable, experimentally inaccessible state, below the melting point, affecting physical and chemical properties of this systems in the stable liquid phase. The presence of the apparent critical point in this mixture has been experimentally observed by Nonlinear Dielectric Effect (NDE) measurements as an anomalous increase in the NDE values typical of critical concentrations. The phase diagram …of this mixture shows evidence that the system freezes in the homogenous phase and its melting point is higher than its critical temperature [1-3]. For such a system, we performed Monte Carlo simulations aimed at analysing the kind of phase transitions observed, and the conditions of their occurrence in a nonpolar/dipolar mixture. We perform studies for classical critical systems of o-nitrotoluene with decane and hexadecane The enthalpy, configurational energy and radial distribution function have been estimated by the MC simulation method in the NPT system. Immiscibility conditions according to Schoen and Hoheisel [4] approach are also discussed. Show more

Keywords: Metastable mixtures, MC simulations, near critical point, nonlinear dielectric effect

DOI: 10.3233/JCM-2010-0327

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 10, no. 3-6, pp. 575-586, 2010

Authors: Soscún, Humberto

Article Type: Research Article

Abstract: The results of ab initio and density functional theory DFT calculations of dipole moments and electronic contributions to static dipole (hyper)polarizabilities of benzaldehyde and thiobenzaldehyde molecules in gas phase are presented. These properties were evaluated at the SCF, MP2, MP4 and DFT (B3LYP) levels of theory with a selection of basis sets that include polarization and diffuse functions on the C, O, S and H atoms: 6-31+G(d,p) (A), 6-311++G(3d,3p) (B), 6-31+G(d*,p) (C) and the Sadlej (D) basis sets, using HF/A, MP2/A and B3LYP/A optimized geometries under the Cs symmetry restriction. The C basis set has been optimized in terms of …the maxima second hyperpolarizability at HF level. Both MP2 and MP4 methods, performed at full electron configuration, have shown to perform well in the calculation of such properties. Considering the basis sets effects, the impact of the electron correlation in the (hyper)polarizabilities of these molecules is analyzed systematically in terms of the differences between MP2 and MP4 perturbation theory and those from DFT(B3LYP) methods. The effects of substitution of the C=S fragment by the C=O group in the benzaldehyde molecule, giving the formation of thiobenzaldehyde, lead to enhanced results of nonlinear optical properties in terms of their first (β) and second hyperpolarizability (γ), that shown to be higher than those for para-Nitroaniline molecules. In fact, thiobenzaldehyde exhibit significant values of nonlinear optical properties which make this chromophore a prospective building block for nonlinear optical materials. Show more

Keywords: Hyperpolarizabilities, HF, MP2, MP4, DFT, benzaldehyde, thiobenzaldehyde

DOI: 10.3233/JCM-2010-0345

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 10, no. 3-6, pp. 587-597, 2010

Authors: Starikov, Vitaly Ivanovich

Article Type: Research Article

Abstract: The results of calculations of He-, Ne-, Ar-, Kr-, and Xe- broadening coefficients of ν1 , ν 2 and ν3 ro-vibrational lines of H2 S molecule are presented and discussed. The calculations were performed in the framework of the Robert-Bonamy method, in which the exact trajectory model was incorporated. Parameters of the interaction potentials, chosen in the form of atom-atom potentials, were optimized to give the best agreement with the existing experimental data. With the exception of the some data the agreement between the calculated and experimentally measured broadening coefficients γ is satisfactory for the ν1 and …ν3 bands of H2 S for all collisional partners. The measured strong J-dependence of helium broadening in the ν2 band did not appear in the calculation. Besides, it was found that an interaction potential for H2 S- He system is ambiguously determined. The optimal set of the parameters for H2 S- He interaction potential was used in the calculation of the helium broadening coefficients for the ν1 band of H2 S (J ⩽ 15, 100 K ⩽ T ⩽ 1000K) and then for their analytical representation. Show more

Keywords: Noble gas broadening, H2S, intermolecular potential, semi-classical impact method, analytical formula for half-widths

DOI: 10.3233/JCM-2010-0346

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 10, no. 3-6, pp. 599-608, 2010

Authors: Swart, Marcel

Article Type: Research Article

Abstract: The principle of minimum polarizability (MPP) has been investigated for the spin states of several transition metal complexes, using methods (OPBE, SSB-D) that are reliable for providing spin-state energies. For all complexes studied, these functionals indeed provide the same ground-state with similar spin-state splittings. The corresponding polarizabilities for each of the spin states however show that there is no correlation between the spin-state energy and its polarizability. Hence, the stability of a given spin-state can not be deduced from its polarizability value, leading to yet another breakdown of the MPP principle.

Keywords: Density functional theory, polarizability, spin states

DOI: 10.3233/JCM-2010-0347

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 10, no. 3-6, pp. 609-614, 2010

Authors: Verma, A.S. | Sharma, Sheetal | Jindal, V.K.

Article Type: Research Article

Abstract: In this paper we present a new expression relating the electronic polarizability (αe ) in terms of ionic charge (Z), melting temperature (Tm ) and mean atomic volume (Ω) for zinc blende (AII BVI and AIII BV ) structured solids. The electronic polarizability of these solids exhibit a linear relationship when plotted against the kB Tm /Ω (kB = Boltzmann's constant), but fall on different straight lines according to the product of the ionic charge of the compounds. We have applied the proposed relation on these solids and found a better agreement with the experimental data as compared to …the values evaluated by earlier researchers. Show more

Keywords: Electronic polarizability, semiconductors, melting temperature, atomic volume

DOI: 10.3233/JCM-2010-0349

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 10, no. 3-6, pp. 615-620, 2010

Authors: Woźniak, S.

Article Type: Research Article

Abstract: The molecular theory of optically induced static magnetization is extended to systems acted on with a dc electric field. The two effects, the invers Faraday effect and invers magnetochiral birefringence, are analysed for their dependence on an electric field perpendicular or parallel to the propagation direction of the incident light beam. The mechanisms responsible for the effects are described in terms of linear and nonlinear multipole polarizability tensors as well as molecular reorientation functions defined by the generalized Langevin-Kielich functions. The effects at electric saturation are a source of information concerning the tensor components of electric dipole, magnetic dipole and …electric quadrupole polarizability. Show more

Keywords: Invers Faraday effect, Invers magnetochiral birefringence, Nonlinear polarizabilitiesv, Generalized Langevin-Kielich functions

DOI: 10.3233/JCM-2010-0325

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 10, no. 3-6, pp. 621-640, 2010

Article Type: Correction

DOI: 10.3233/JCM-2010-0356

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 10, no. 3-6, pp. 641-641, 2010