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George Maroulis - One of the best experts on this subject based on the ideXlab platform.
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nonlinear properties and collisional spectra in hydrogen heavy noble gas atom mixtures
2012Co-Authors: Waldemar Glaz, Tadeusz Bancewicz, George Maroulis, Anastasios Haskopoulos, J L GodetAbstract:In a series of previously published works the phenomenon of collision induced nonlinear hyper-Rayleigh scattering of light (CIHRS) was studied on the basis of the numerical quantum chemistry (QC) methods confronted with a theoretical approach. A class of super-molecular systems composed of hydrogen (H2) and lighter inert gas atoms (Rg) was considered. In this report a development of this research work is presented with more massive and highly polarizable, Kr and Xe, perturbers involved. The collision-induced Hyperpolarizability tensorial values, Δβ obtained by means of the QC ab initio methods are applied in order to produce the CIHRS spectral distributions; the influence of Δβ features on the line shapes is compared with the earlier theoretical predictions. Namely, the validity of the multipole-induced-multipole (MIM) mechanism is assessed. In particular, its relevance to reproduce long-range functional behavior of the so-called symmetry adapted (SA) components of the Hyperpolarizability tensor Δβ(R) is discussed. A thorough analysis of the translational CIHRS spectra is then performed to identify the role of the Hyperpolarizability spatial distribution in forming particular sections of the line shapes. An extension of the dipole-induced-quadrupole analytical model is suggested and tested with regard to its ability to reproduce more accurate profiles.
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Hyperpolarizability of gaas dimer is not negative
2007Co-Authors: George Maroulis, Panaghiotis Karamanis, Claude PouchanAbstract:We present a systematic study of the static electric Hyperpolarizability of Ga2As2. The authors rely on finite-field high-level ab initio calculations with carefully optimized basis sets. Their best values for the mean and the anisotropy of the dipole polarizability are α¯=158.57 and Δα=130.33e2a02Eh−1. For the Hyperpolarizability we propose an estimate γ¯=(155±15)×103e4a04Eh−3, which does not agree with the negative value predicted by Lan et al. [J. Chem. Phys. 124, 094302 (2006)]. Density functional theory based methods yield values close to those predicted by conventional ab initio methods. The (hyper)polarizability components are particularly enhanced along the direction defined by the Ga–Ga axis.
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is the Hyperpolarizability of cu2 negative a study of basis set and electron correlation effects
2003Co-Authors: George MaroulisAbstract:The dipole (hyper)polarizability of the copper dimer has been obtained from conventional ab initio and density functional theory calculations. A very large (23s16p12d6f) basis set consisting of 346 Gaussian-type functions is thought to provide reference results of near-Hartree−Fock quality for all properties. We obtain ᾱ = 102.54 and Δα = 41.89 for the mean and the anisotropy of the dipole polarizability (ααβ/e2a02Eh-1). For the Cartesian components and the mean of the Hyperpolarizability (10-3γαβγδ/e4a04Eh-3) we obtain γzzzz = 309, γxxxx = 209, γxxzz = 87, and γ = 244. Electron correlation lowers ᾱ but increases considerably Δα. The effect on the Hyperpolarizability is enormous, as the longitudinal component γzzzz is drastically reduced, while γxxxx and γxxzz are nearly halved. At the CCSD(T) level of theory with a [7s6p6d2f] basis set we obtain ᾱ = 93.82, Δα = 67.09 and γzzzz = 18, γxxxx = 101, γxxzz = 35, and γ = 86. The dipole polarizability varies as [ᾱ(R) − ᾱ(Re)]/e2a02Eh-1 = 28.09(R − Re) + 4.69(...
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accurate electric multipole moment static polarizability and Hyperpolarizability derivatives for n2
2003Co-Authors: George MaroulisAbstract:We report accurate values of the electric moments, static polarizabilities, hyperpolarizabilities and their respective derivatives for N2. Our values have been extracted from finite-field Moller–Pleset perturbation theory and coupled cluster calculations performed with carefully designed basis sets. A large [15s12p9d7f] basis set consisting of 290 CGTF is expected to provide reference self-consistent-field values of near-Hartree–Fock quality for all properties. The Hartree–Fock limit for the mean Hyperpolarizability is estimated at γ=715±4e4a04Eh−3 at the experimental bond length Re=2.074 32a0. Accurate estimates of the electron correlation effects were obtained with a [10s7p6d4f] basis set. Our best values are Θ=−1.1258ea02 for the quadrupole and Φ=−6.75ea04 for the hexadecapole moment, ᾱ=11.7709 and Δα=4.6074e2a02Eh−1 for the mean and the anisotropy of the dipole polarizability, C=41.63e2a04Eh−1 for the mean quadrupole polarizability and γ=927e4a04Eh−3 for the dipole Hyperpolarizability. The latter v...
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electric quadrupole and hexadecapole moment dipole and quadrupole polarizability second electric dipole Hyperpolarizability for p2 and a comparative study of molecular polarization in n2 p2 and as2
2003Co-Authors: George Maroulis, Demetrios XenidesAbstract:We have obtained electric properties of P⋮P from finite-field Moller−Plesset perturbation theory, density functional theory and coupled cluster techniques. Reference, near-Hartree−Fock values have been obtained with a very large (20s15p10d5f) uncontracted basis set consisting of 300 Gaussian-type functions. At the experimental equilibrium bond length of Re = 1.8934 A we obtain self-consistent field values of 1.0682 ea02 for the quadrupole moment (ϑ), −41.68 ea04 for the hexadecapole moment (Φ), 51.16 for the mean ( ) and 28.58 e2a02Eh-1 for the anisotropy of the dipole polarizability, and 16.5 × 103 e4a04Eh-3 for the mean second dipole Hyperpolarizability ( ). Electron correlation reduces strongly the magnitude of the electric moments. Both components of the dipole polarizability are reduced by electron correlation, but a small increase is observed for the dipole Hyperpolarizability. Our best post-Hartree−Fock values have been obtained with a [9s7p5d3f] basis set at the CCSD(T) level of theory: ϑ = 0.485...
Benoit Champagne - One of the best experts on this subject based on the ideXlab platform.
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how the second order nonlinear optical response of the collagen triple helix appears a theoretical investigation
2014Co-Authors: Marc De Wergifosse, Jerome De Ruyck, Benoit ChampagneAbstract:The origin and the nature of the first Hyperpolarizability of collagen has been unraveled by performing first-principles calculations on the PPG10 compound, a molecular model for the collagen tripl...
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assessing long range corrected functionals with physically adjusted range separated parameters for calculating the polarizability and the second Hyperpolarizability of polydiacetylene and polybutatriene chains
2014Co-Authors: Sebastien Nenon, Benoit Champagne, Milena SpassovaAbstract:The use of physically-adjusted range-separated parameter (μ) together with long-range corrected exchange–correlation functionals is shown not to be reliable for calculating the polarizability (α) and the second Hyperpolarizability (γ) of large π-conjugated systems. This statement has been substantiated by calculating the polarizability and the second Hyperpolarizability of increasingly large polydiacetylene and polybutatriene chains in comparison with reference data evaluated at the coupled-cluster singles and doubles with perturbative estimation of the triples [CCSD(T)] level. Further comparisons highlight that long-range corrected exchange–correlation functionals with conventional and larger range-separated parameters perform better for α (μ = 0.47) and γ (μ = 0.33 and 0.47) but for polybutatriene chains none can describe satisfactorily the chain length evolution of γ. On the other hand, Moller–Plesset second- and fourth-order values are in closer agreement with CCSD(T), except for γ of polybutatriene, which is strongly overestimated.
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nonlinear optical properties of flavylium salts a quantum chemical study
2010Co-Authors: Elena Bogdan, Benoit Champagne, Lea Rougier, Laurent Ducasse, Frederic CastetAbstract:Ab initio calculations have been carried out to unravel the relationships between the structure and the first Hyperpolarizability in flavylium derivatives, with the aim to design efficient second-order nonlinear optical (NLO) switching compounds. Large contrasts of the first Hyperpolarizability have been obtained along the pH-controlled and photoinduced transformations for specific combinations of chemical substituents in the 4′- and 7-positions, which demonstrates that these multistate systems should behave as highly efficient molecular NLO switches.
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theoretical investigation of the dynamic first Hyperpolarizability of dha vhf molecular switches
2009Co-Authors: Benoit Champagne, Elena Bogdan, Laurent Ducasse, Frederic Castet, Aurelie Plaquet, Vincent Rodriguez, Jeanluc PozzoAbstract:The contrast of second-order nonlinear optical response in the dihydroazulene (DHA)-vinylheptafulvene (VHF) equilibrium has been investigated as a function of the nature of the substituent (R) on the phenyl ring by means of quantum chemistry calculations including electron correlation, frequency dispersion, and solvent effects. By considering the hyper-Rayleigh scattering (HRS) response, the contrast for R = H and R = CH3 between the DHA and VHF forms is larger than 5 while the contrast between the cis and transVHF forms is close to 1. Adding the NH2 donor group in para position of the phenyl leads to a substantial increase of the HRS first Hyperpolarizability of the three forms, which is detrimental to the contrast. Then, in the case of the NO2 acceptor group, a contrast is recovered because the HRS first Hyperpolarizability of the DHA form is about 2–3 times larger than for both VHF forms. These variations of first Hyperpolarizability as a function of the substituents as well as the associated contrasts have been explained in terms of donor/acceptor strengths and geometrical parameters.
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second Hyperpolarizability of zethrenes
2007Co-Authors: Benoit Champagne, Takashi Kubo, Hideaki Takahashi, Masayoshi Nakano, Akihito Takebe, Masahito Nate, Edith Botek, Kenji Kamada, Ryohei Kishi, Koji OhtaAbstract:We report a study on the static second hyperpolarizabilities (γ) of zethrenes using the UBHandHLYP hybrid density functional theory method. Though zethrenes were originally considered as closed-shell systems, the values of their diradical characters, calculated from the occupation numbers of spin-unrestricted Hartree-Fock natural orbitals (UNOs), demonstrate an open-shell diradical nature, which increases with the size of the middle ring region because of the recovery of the aromaticity in that region. As references, we examine also the γ values of tetrabenzopolyacenes, which are regarded as the corresponding closed-shell systems due to their negligible diradical characters. It is found that the longitudinal γ values for zethrenes are much larger than those of the corresponding reference closed-shell systems, whereas their ratio, γ(zethrene)/γ(reference), is reduced when increasing the length of middle ring regions, i.e., when increasing the diradical character.
Mark G. Kuzyk - One of the best experts on this subject based on the ideXlab platform.
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a new dipole free sum over states expression for the second Hyperpolarizability
2008Co-Authors: Javier Perezmoreno, Koen Clays, Mark G. KuzykAbstract:The generalized Thomas-Kuhn sum rules are used to eliminate the explicit dependence on dipolar terms in the traditional sum-over-states (SOS) expression for the second Hyperpolarizability to derive a new, yet equivalent, SOS expression. This new dipole-free expression may be better suited to study the second Hyperpolarizability of nondipolar systems such as quadrupolar, octupolar, and dodecapolar structures. The two expressions lead to the same fundamental limits of the off-resonance second Hyperpolarizability; and when applied to a particle in a box and a clipped harmonic oscillator, have the same frequency dependence. We propose that the new dipole-free equation, when used in conjunction with the standard SOS expression, can be used to develop a three-state model of the dispersion of the third-order susceptibility that can be applied to molecules in cases where normally many more states would have been required. Furthermore, a comparison between the two expressions can be used as a convergence test of molecular orbital calculations when applied to the second Hyperpolarizability.
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optimizing potential energy functions for maximal intrinsic Hyperpolarizability
2007Co-Authors: Juefei Zhou, David S Watkins, Urszula B Szafruga, Mark G. KuzykAbstract:We use numerical optimization to study the properties of (1) the class of one-dimensional potential energy functions and (2) systems of point nuclei in two dimensions that yield the largest intrinsic hyperpolarizabilities, which we find to be within 30% of the fundamental limit. In all cases, we use a one-electron model. It is found that a broad range of optimized potentials, each of very different character, yield the same intrinsic Hyperpolarizability ceiling of 0.709. Furthermore, all optimized potential energy functions share common features such as (1) the value of the normalized transition dipole moment to the dominant state, which forces the Hyperpolarizability to be dominated by only two excited states and (2) the energy ratio between the two dominant states. All optimized potentials are found to obey the three-level ansatz to within about 1%. Many of these potential energy functions may be implementable in multiple quantum well structures. The subset of potentials with undulations reaffirm that modulation of conjugation may be an approach for making better organic molecules, though there appear to be many others. Additionally, our results suggest that one-dimensional molecules may have larger diagonal intrinsic Hyperpolarizability ${\ensuremath{\beta}}_{xxx}^{\mathrm{int}}$ than higher-dimensional systems.
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fundamental limits of all nonlinear optical phenomena that are representable by a second order nonlinear susceptibility
2006Co-Authors: Mark G. KuzykAbstract:Applying the three-level ansatz and the sum rules to the new dipole-free sum-over-states expression, we develop a rigorous method for calculating the fundamental limits of the dispersion of the real and imaginary parts of the second-order electronic nonlinear-optical susceptibilities. These results can be applied to all orders of nonlinearity, hence can be used to study any nonlinear-optical phenomena at any wavelength. The theory can be used to understand how strongly light interacts with matter and can be applied to optimizing a material’s properties for applications. In particular, we find that the resonant first Hyperpolarizability peaks when the energy difference between excited states is small. In contrast, the maximal off-resonance Hyperpolarizability requires the excited states to be well separated. Therefore, one molecular design strategy does not fit all applications.
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modulated conjugation as a means for attaining a record high intrinsic Hyperpolarizability
2006Co-Authors: Javier Perezmoreno, Koen Clays, Yuxia Zhao, Mark G. KuzykAbstract:We report on a series of chromophores that have been synthesized with a modulated conjugation path between donor and acceptor. Hyper-Rayleigh scattering measurements of the best molecule show an enhanced intrinsic Hyperpolarizability that breaches the apparent limit of all previously studied molecules.
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pushing the Hyperpolarizability to the limit
2006Co-Authors: Juefei Zhou, Mark G. Kuzyk, David S WatkinsAbstract:We use numerical optimization to find a one-dimensional potential energy function that yields the largest Hyperpolarizability, which we find is within 30% of the fundamental limit. Our results reveal insights into the character of the potential energy functions and wavefunctions that lead to the largest Hyperpolarizability. We suggest that donor-acceptor molecules with a conjugated bridge with many sites of reduced conjugation to impart conjugation modulation may be the best paradigm for making materials with huge hyperpolarizabilities that approach the fundamental limit.
A V Taichenachev - One of the best experts on this subject based on the ideXlab platform.
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optical lattice induced light shifts in an yb atomic clock
2008Co-Authors: Z W Barber, J E Stalnaker, Nathan D Lemke, N Poli, C W Oates, Tara M Fortier, Scott A Diddams, L Hollberg, Chad Hoyt, A V TaichenachevAbstract:We present an experimental study of the lattice-induced light shifts on the (1)S(0) --> (3)P(0) optical clock transition (nu(clock) approximately 518 THz) in neutral ytterbium. The "magic" frequency nu(magic) for the 174Yb isotope was determined to be 394 799 475(35) MHz, which leads to a first order light shift uncertainty of 0.38 Hz. We also investigated the Hyperpolarizability shifts due to the nearby 6s6p(3)P(0) --> 6s8p(3)P(0), 6s8p(3)P(2), and 6s5f(3)F(2) two-photon resonances at 759.708, 754.23, and 764.95 nm, respectively. By measuring the corresponding clock transition shifts near these two-photon resonances, the Hyperpolarizability shift was estimated to be 170(33) mHz for a linear polarized, 50 microK deep, lattice at the magic wavelength. These results indicate that the differential polarizability and Hyperpolarizability frequency shift uncertainties in a Yb lattice clock could be held to well below 10(-17).
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optical lattice induced light shifts in an yb atomic clock
2008Co-Authors: Z W Barber, J E Stalnaker, Nathan D Lemke, N Poli, C W Oates, Tara M Fortier, Scott A Diddams, L Hollberg, Chad Hoyt, A V TaichenachevAbstract:We present an experimental study of the lattice-induced light shifts on the {sup 1}S{sub 0}{yields}{sup 3}P{sub 0} optical clock transition ({nu}{sub clock}{approx_equal}518 THz) in neutral ytterbium. The 'magic' frequency {nu}{sub magic} for the {sup 174}Yb isotope was determined to be 394 799 475(35) MHz, which leads to a first order light shift uncertainty of 0.38 Hz. We also investigated the Hyperpolarizability shifts due to the nearby 6s6p{sup 3}P{sub 0}{yields}6s8p{sup 3}P{sub 0}, 6s8p{sup 3}P{sub 2}, and 6s5f{sup 3}F{sub 2} two-photon resonances at 759.708, 754.23, and 764.95 nm, respectively. By measuring the corresponding clock transition shifts near these two-photon resonances, the Hyperpolarizability shift was estimated to be 170(33) mHz for a linear polarized, 50 {mu}K deep, lattice at the magic wavelength. These results indicate that the differential polarizability and Hyperpolarizability frequency shift uncertainties in a Yb lattice clock could be held to well below 10{sup -17}.
Koen Clays - One of the best experts on this subject based on the ideXlab platform.
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a new dipole free sum over states expression for the second Hyperpolarizability
2008Co-Authors: Javier Perezmoreno, Koen Clays, Mark G. KuzykAbstract:The generalized Thomas-Kuhn sum rules are used to eliminate the explicit dependence on dipolar terms in the traditional sum-over-states (SOS) expression for the second Hyperpolarizability to derive a new, yet equivalent, SOS expression. This new dipole-free expression may be better suited to study the second Hyperpolarizability of nondipolar systems such as quadrupolar, octupolar, and dodecapolar structures. The two expressions lead to the same fundamental limits of the off-resonance second Hyperpolarizability; and when applied to a particle in a box and a clipped harmonic oscillator, have the same frequency dependence. We propose that the new dipole-free equation, when used in conjunction with the standard SOS expression, can be used to develop a three-state model of the dispersion of the third-order susceptibility that can be applied to molecules in cases where normally many more states would have been required. Furthermore, a comparison between the two expressions can be used as a convergence test of molecular orbital calculations when applied to the second Hyperpolarizability.
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combined molecular and supramolecular bottom up nanoengineering for enhanced nonlinear optical response experiments modeling and approaching the fundamental limit
2007Co-Authors: Javier Perezmoreno, Inge Asselberghs, Kai Song, Koen Clays, Yuxia Zhao, Hachiro Nakanishi, Shuji Okada, Kyoko Nogi, Ohkil Kim, Janka MatraiAbstract:The authors study the combination of two independent strategies that enhance the Hyperpolarizability of ionic organic chromophores. The first molecular-level strategy is the extension of the conjugation path in the active chromophore. The second supramolecular-level strategy is the bottom-up nanoengineering of an inclusion complex of the chromophore in an amylose helix by self-assembly. The authors study a series of five (dimethylamino)stilbazolium-type chromophores with increasing conjugation length between the (dimethylamino)phenyl donor ring and the pyridinium acceptor ring in conjunction with four amylose helices of differing molecular weights. The first hyperpolarizabilities of the self-assembled inclusion complexes, as determined with frequency-resolved femtosecond hyper-Rayleigh scattering at 800 and 1300nm, are compared with experimental values for the free chromophores in solution and with theoretical values. While the experimental values for the Hyperpolarizability in solution are lower than the...
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modulated conjugation as a means for attaining a record high intrinsic Hyperpolarizability
2006Co-Authors: Javier Perezmoreno, Koen Clays, Yuxia Zhao, Mark G. KuzykAbstract:We report on a series of chromophores that have been synthesized with a modulated conjugation path between donor and acceptor. Hyper-Rayleigh scattering measurements of the best molecule show an enhanced intrinsic Hyperpolarizability that breaches the apparent limit of all previously studied molecules.
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why experimental hyperpolarizabilities fall short of the fundamental limits and new approaches for breaking this barrier
2005Co-Authors: Mark G. Kuzyk, Javier Perezmoreno, Inge Asselberghs, Kai Song, Koen Clays, Yuxia Zhao, Janka Matrai, Kakali Tripathi, Marc De Maeyer, Benjamin J CoeAbstract:Sum rules have been shown to impose a fundamental limit on the of nonlinear-optical susceptibility. All of the measured values of the Hyperpolarizability and second Hyperpolarizability over the last 25+ years, be it on- or off-resonance, fall a factor of 103/2 below these limits. Not only is this result scientifically puzzling on a fundamental level; but, has implications on the kinds of practical devices that can be made. In this work, we discuss molecular engineering techniques that aim to break this bottleneck.
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in situ reversible electrochemical switching of the molecular first Hyperpolarizability
2003Co-Authors: Inge Asselberghs, Koen Clays, Andre Persoons, Andrew M Mcdonagh, Michael D Ward, Jon A McclevertyAbstract:In situ reversible electrochemical switching of the molecular second-order nonlinear optical (NLO) polarizability, or first Hyperpolarizability, has been implemented in a specially designed cell.The redox-switchable NLO chromophore is based on the octamethylferrocene/octamethylferrocenium redox system as electron-donor (D) group, in conjunction with nitrothiophene as the electron-acceptor (A) group and ethenyl as the p-conjugation bridge.This D- p-A chro- mophore has been shown to exhibit reversible redox switching of its linear and nonlinear optical properties.The im- portance and potential of this electrochemical switching of the first Hyperpolarizability is discussed in the context of current and future applications of second-order NLO effects. 2002 Elsevier Science B.V. All rights reserved.