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International audience; We propose a family of photonic materials based on nickel bis(dithiolene) [NiBDT] and benzene (B). Linear and planar oligomers of 1D and 2D polymers, together with several rich π-electron linkers (e.g. C14H8, C24H8, and C4O2H4), have been employed in order to demonstrate the superior performance of the proposed materials. A key property for the design of efficient photonic materials is the second hyperpolarizability. We have, thus, computed it together with several other properties, such as the dipole moment, polarizability, first excitation energy, etc. We have also used two indices to estimate the degree of the diradical character of the considered derivatives. The calculations have been performed by employing density functional theory. Considerable care has been taken to validate the computational procedure we have used. The main findings of the present work are as follows: (a) the 1D and 2D coordination polymers based on nickel bis(dithiolene) and benzene and in particular the linear ones, (B-NiBDT)n, are very likely to be efficient photonic materials, since they have gigantic second hyperpolarizability. (b) The second hyperpolarizability greatly depends on the organic linker with which NiBDT is fused and on the structure; for example, the linear oligomers have much higher second hyperpolarizability than the planar ones. The present work together with a recent article (A. Avramopoulos et al., J. Phys. Chem. C, 2016, 120, 9419-9435) demonstrates a mechanism for designing efficient photonic materials.

International audience; A systematic analysis of the molecular structure, energetics, electronic (hyper)​polarizabilities and their interaction-​induced counterparts of C60 with a series of molecular graphene (MG) models, CmHn, where m = 24, 84, 114, 222, 366, 546 and n = 12, 24, 30, 42, 54, 66, was performed. All the reported data were computed by employing density functional theory and a series of basis sets. The main goal of the study is to investigate how alteration of the size of the MG model affects the strength of the interaction, charge rearrangement, and polarization and interaction-​induced polarization of the complex, C60-​MG. A Hirshfeld-​based scheme has been employed in order to provide information on the intrinsic polarizability density representations of the reported complexes. It was found that the interaction energy increases approaching a limit of -​26.98 kcal​/mol for m = 366 and 546; the polarizability and second hyperpolarizability increase with increasing the size of MG. An opposite trend was observed for the dipole moment. Interestingly, the variation of the first hyperpolarizability is relatively small with m. Since polarizability is a key factor for the stability of molecular graphene with nucleobases (NB)​, a study of the magnitude of the interaction-​induced polarizability of C84H24-​NB complexes is also reported, aiming to reveal changes of its magnitude with the type of NB. The binding strength of C84H24-​NB complexes is also computed and found to be in agreement with available theoretical and experimental data. The interaction involved in C60 B12N12H24-​NB complexes has also been considered, featuring the effect of contamination on the binding strength between MG and NBs.

The linear and nonlinear optical properties (L&NLO) of a monolayer of (4-(N-methyl-N-(carboxypropyl)amino)-phenyl-4′-(N,N-dibutylamino)phenylsquaraine (SBA) were computed by a combination of molecular dynamics simulations, molecular quantum-mechanical, and discrete local-field model calculations to compute the macroscopic optical susceptibilities. Langmuir films on water and graphite were simulated and several structural properties investigated. In addition, SBA in water and dimethylsulfoxide (DMSO) solutions were simulated, and the aggregation behavior of SBA in these solvents was analyzed. The molecular (hyper)polarizabilities of SBA were calculated with density functional theory and validated with MP2 correlated ab initio calculations. An unusual large component perpendicular to the molecular dipole moment is obtained for the molecular first hyperpolarizability, which is a main contributor to the large in-plane anisotropy of the computed macroscopic second-harmonic generation signal of the Langmuir–Blo...

In the present study, we report on the results of computations of the electronic and the vibrational contributions to the static first hyperpolarizability ( β ) of meta-dinitrobenzene molecule. It turned out that the electron correlation effects are much more important for reliable prediction of the electronic counterpart than for determining vibrational corrections: β e value is increased by about 500% passing from the HF to the CCSD(T) level of theory. The preliminary assessment of density functional theory in determination of hyperpolarizabilities shows that harmonic contributions to β , contrary to the purely electronic contributions, are substantially underestimated in comparison with the wave function theory results. Another important finding of this study is that long-range corrected functionals tend to improve upon traditional functionals both in determining electronic as well as vibrational hyperpolarizabilities. It is also demonstrated that the vibrations of the nitro groups have a predominant influence on the vibrational contributions to β vib . The mechanical and electrical anharmonicity correction terms to the vibrational hyperpolarizability were found to be substantially larger than the lowest-order harmonic term.

A systematic study of the (hyper)polarizabilities of a series of Xe compounds, HXeF, AuXeF and XeAuF has been performed. A consistent hierarchy of basis sets and ab-initio methods involving HF, MP2, CCSD and CCSD(T), has been employed in order to investigate in depth the effect of Xe insertion on the above properties of HF and AuF. It was observed that the Xe position in AuF significantly modifies the (hyper)polarizability of the resulting derivative. The polarizability and first hyperpolarizability of AuXeF are remarkably larger than that of XeAuF.

The linear and nonlinear optical (L&NLO) properties of the recently synthesized Xenon compounds HXeOH and HXeSH are studied. For this purpose a hierarchy of basis sets in connection with the widely used electron correlation methods, MP2, CCSD, CCSD(T), were employed in order to discuss the dipole moment, polarizability and first hyperpolarizability of these compounds. It was found that Xe insertion has a great effect on the hyperpolarizability of H2O and H2S. A significant electron correlation contribution was also observed, in particular for HXeSH. The strongly ionic character (H-Xe)+ (A-H)−, where A=O or S, of these compounds was elucitated by employing a natural bond orbital analysis. The enhanced NLO response of the studied species has been rationalized by employing a two-state model.

This is the second part of a study to elucidate the local field effects on the nonlinear optical properties of p-nitroaniline (pNA) in three solvents of different multipolar character, that is, cyclohexane (CH), 1,4-dioxane (DI), and tetrahydrofuran (THF), employing a discrete description of the solutions. By the use of liquid structure information from molecular dynamics simulations and molecular properties computed by high-level ab initio methods, the local field and local field gradients on p-nitroaniline and the solvent molecules are computed in quadrupolar approximation. To validate the simulations and the induction model, static and dynamic (non)linear properties of the pure solvents are also computed. With the exception of the static dielectric constant of pure THF, a good agreement between computed and experimental refractive indices, dielectric constants, and third harmonic generation signals is obtained for the solvents. For the solutions, it is found that multipole moments up to two orders higher than quadrupole have a negligible influence on the local fields on pNA, if a simple distribution model is employed for the electric properties of pNA. Quadrupole effects are found to be nonnegligible in all three solvents but are especially pronounced in the 1,4-dioxane solvent, in which the local fields are similar to those in THF, although the dielectric constant of DI is 2.2 and that of the simulated THF is 5.4. The electric-field-induced second harmonic generation (EFISH) signal and the hyper-Rayleigh scattering signal of pNA in the solutions computed with the local field are in good to fair agreement with available experimental results. This confirms the effect of the "dioxane anomaly" also on nonlinear optical properties. Predictions based on an ellipsoidal Onsager model as applied by experimentalists are in very good agreement with the discrete model predictions. This is in contrast to a recent discrete reaction field calculation of pNA in 1,4-dioxane, which found that the predicted first hyperpolarizability of pNA deviated strongly from the predictions obtained using Onsager-Lorentz local field factors.

The electronic and vibrational contributions to the dipole moment, polarizabilities, and first hyperpolarizabilities of HArF are reported. These have been computed by using a series of systematically built basis sets and a hierarchy of computational methods. HArF has a very large first hyperpolarizability along the z axis. This has been rationalized by invoking the difference in the electronic structure between the ground and the first excited state. The argon fluorohydride has been recently derived and characterized. The present study provides complementary data for the understanding of the electronic structure of this interesting argon derivative.

As part of a program to investigate the linear and nonlinear susceptibilities of acetonitrile in the condensed phase, we report on the accurate calculation of the molecular electric properties of acetonitrile, taking intoaccount geometry and basis set effects, static and dynamic electronic correlation, vibrational contributions, and frequency dispersion. All correlated single reference state methods as well as the multireference SCF with a Moller-Plesset second-order perturbation correction (MRMP2) yield similar values for the electronic contribution to the polarizability a and the second hyperpolarizability y. For the first hyperpolarizability, however, differences between the highly correlated methods CCSD(T) and MRMP2 remain. Vibrational contributions to the electric properties are calculated analytically and using two numerical finite difference methods at the Hartree-Fock level and at the correlated second-order Moller-Plesset level using finite field difference methods. Basis set convergence and convergence with the level of anharmonicity are examined. Computed values of the quantity μβ∥ (-2ω; ω, ω)/(3kT) + γ a v (-2ω; ω, ω, 0) agree with temperature-dependent experimental values at two different frequencies within 10%. Using the highest correlated methods, liquid-phase susceptibilities are computed in the dipolar Onsager reaction-field approximation. Excellent agreement with experiment for the relative permittivity and the refractive indices is found as well as acceptable agreement for the nonlinear susceptibility.

cited By 6; International audience; Starting from a hypothetical but fundamental charge/discharge sequence, the topic of nonlinear optical switching in atomic clusters built from silicon and alkali metals is opened up. The outcomes presented in this work, obtained with ab initio methods of exceptional predictive capabilities, offer strong evidences that sizable hyperpolarizability contrasts between neutral and charged alkali metal doped cluster forms might be simultaneously accomplished. The observed switching procedure involves redox polyatomic clusters formed by Si atoms. These centers function as electron acceptors at the ground state and as electron donors at the excited states facilitating low energy charge transfer transitions upon electronic excitation. © 2014 Wiley Periodicals, Inc. Accurate ab initio computations suggest that sizable hyperpolarizability contrasts between neutral and charged alkali metal doped silicon clusters might be simultaneously accomplished. The observed effect involves redox polyatomic centers formed by Si atoms. These centers function as electron acceptors at the ground state and as electron donors at the excited states, facilitating low energy charge-transfer transitions upon electronic excitation. © 2014 Wiley Periodicals, Inc.

The macroscopic first- to third-order susceptibilities of naphthalene, anthracene and meta-nitroaniline (mNA) are calculated using a rigorous local field approach. Molecular (hyper)polarizabilities used as input are determined by density functional theory calculations with specially designed basis sets and for mNA also by MP2 calculations with the 6-31++G** basis set. In the case of mNA, the permanent electric local field due to the surrounding dipoles in the crystal is taken into account for the first- and second-order susceptibility by a self-consistent approach. The molecular dipole moment and first hyperpolarizability of mNA are drastically changed by the permanent local field. In all cases the calculated first-order susceptibility compares very favorably with experimental data, if the molecular response is distributed over all heavy atoms in the molecules. Similarly, the calculated second-order susceptibility for mNA is in good agreement with available experimental data, if the same distribution scheme is used and the permanent local field is taken into account properly. This implies that accurate values for the molecular second-order hyperpolarizability c have to be available. The anisotropic Lorentz field factor approximation yields results that are only slightly worse than the best ones of the rigorous local field theory for the first-order susceptibilities, but fails for the second-order susceptibility of mNA, due to its incapability to describe the large eAect of the permanent local field on the first-order hyperpolarizability b. ” 2000 Elsevier Science B.V. All rights reserved.

We present a semi-numerical method based on Numerov–Cooley (NC) integration for calculating vibrational corrections to static electric properties of diatomic molecules. The approach exploits the Born–Oppenheimer energy and property functions, utilizing such information in the NC integration of the field-dependent vibrational equation, in a way which exposes separate contributions to the total electric property. The scheme is illustrated by computation of electronic and vibrational contributions to the dipole polarizability and first hyperpolarizability of the KLi dimer. A comparison with results obtained from finite-order perturbation theory reveals various sources of anharmonicity.

The electronic structure of the fully lithiated benzene molecule has been calculated at different levels of approximation with particular attention paid to its second hyperpolarizability. It has been estimated that lithiation of the benzene molecule may lead to the enormous increase of the second hyperpolarizability. For hexalithiobenzene the second hyperpolarizability term responsible for the third harmonic generation has been estimated to be of the order of 107e4ao4Eh−3. The reasons for the very large increase of the dipole polarizability, and in particular, of the second hyperpolarizability upon lithiation have been analysed in terms of the electronic structure, orbital energy levels, and the excitation spectrum of the hexalithiobenzene molecule. The main factor responsible for the particularly large values of the studied properties is the electronic valence shell structure of the lithium atom. Although the hexalithiobenzene molecule is used as a model for the study of the lithiation effect, several stable organometallic systems involving alkali metals are known. The present study suggests that among these systems one may find materials of extremly high nonlinear optical efficiency.

Macroscopic first-, second-, and third-order susceptibilities of the urea crystal are calculated using static and frequency-dependent ab initio molecular (hyper)polarizabilities at the self-consistent field (SCF) and second-order-Mo/ller–Plesset (MP2) levels. Environmental effects are taken into account using a rigorous local-field theory and are compared with the anisotropic Lorentz field factor approximation. The electric field arising from the permanent dipoles of the surrounding molecules is explicitly taken into account using a self-consistent approach. The dipole moment and the first hyperpolarizability are particularly strongly dependent on this field, but the crystal structure leads to a fortuitous cancellation of the field effect on the second-order susceptibility. The experimental linear susceptibility is accurately reproduced, while differences remain for the quadratic susceptibility. Dispersion curves for the first-order susceptibility, and results for quadratic electrooptic effect (QEO), elec...

The beryllium atom embedded in He clusters of octahedral and cubic symmetry is studied as a model of a highly polarizable system surrounded by a relatively inert and weakly polarizable medium. The coupled cluster calculations with single and double excitations corrected for triple excitations predict that the dipole polarizability and hyperpolarizability of the `in-cluster' Be atom are significantly reduced in comparison with the free-atom values. In the vicinity of the van der Waals minima this reduction amounts to about ten percent of the Be atom hyperpolarizability. This orbital compression effect shows that in the modeling of highly nonlinear optical materials one must explicitly consider the presence of the medium.

A set of exchange-correlation functionals, including BLYP, PBE0, B3LYP, BHandHLYP, CAM-B3LYP, LC-BLYP, and HSE, has been used to determine static and dynamic nonresonant (nuclear relaxation) vibrational (hyper)polarizabilities for a series of all-trans polymethineimine (PMI) oligomers containing up to eight monomer units. These functionals are assessed against reference values obtained using the Moller–Plesset second-order perturbation theory (MP2) and CCSD methods. For the smallest oligomer, CCSD(T) calculations confirm the choice of MP2 and CCSD as appropriate for assessing the density functionals. By and large, CAM-B3LYP is the most successful, because it is best for the nuclear relaxation contribution to the static linear polarizability, intensity-dependent refractive index second hyperpolarizability, static second hyperpolarizability, and is close to the best for the electro-optical Pockels effect first hyperpolarizability. However, none of the functionals perform satisfactorily for all the vibrational (hyper)polarizabilities studied. In fact, in the case of electric field-induced second harmonic generation all of them, as well as the Hartree–Fock approximation, yield the wrong sign. We have also found that the Pople 6–31+G(d) basis set is unreliable for computing nuclear relaxation (hyper)polarizabilities of PMI oligomers due to the spurious prediction of a nonplanar equilibrium geometry. © 2013 Wiley Periodicals, Inc.

The vibrational (hyper)polarizabilities of some selected Xe derivatives are studied in the context of Bishop–Kirtman perturbation theory (BKPT) and numerical finite field methodology. It was found that for this set of rare gas compounds, the static vibrational properties are quite large, in comparison to the corresponding electronic ones, especially those of the second hyperpolarizability. This also holds for the dc-Pockels β(−ω;ω,0), Kerr γ(−ω;ω,0,0) and electric field second harmonic generation γ (−2ω;ω,ω,0) effects, although the computed nuclear relaxation (nr) vibrational contributions are smaller in magnitude than the static ones. HXeOXeH was used to study the effects of electron correlation, basis set, and geometry. Geometry effects were found to lead to noticeable changes of the vibrational and electronic second hyperpolarizability. A limited study of the effect of Xe insertion to the nr vibrational properties is also reported. Assessment of the results revealed that Xe insertion has a remarkable effect on the nr (hyper)polarizabilities. In terms of the BKPT, this is associated with a remarkable increase of the electrical and mechanical anharmonicity terms. The latter is consistent with the anharmonic character of several vibrational modes reported for rare gas compounds. © 2013 Wiley Periodicals, Inc.

The linear and nonlinear optical (L&NLO) properties, the energy difference between the highest occupied molecular orbital and the lowest unoccupied molecular orbital (HOMO–LUMO gap), the first excitation energy (Eexc), and four indices for the evaluation of the diradical character (DC) of a series of Ni dithiolene derivatives have been computed by employing density functional theory (DFT). The selected DFT functionals provide reliable results for several properties [e.g., excitation energies and (hyper)polarizabilities]. An Atoms in Molecules analysis has been performed and several related properties have been reported (e.g., the average delocalization index, charge density, and its Laplacian). The selected derivatives with regular structural changes allow us to trace correlations between the (hyper)polarizabilities and some of the computed properties (e.g., Eexc and the DC indices). A small change in the structure may lead to a very large change of the diradical character and the L&NLO properties. Several of the studied derivatives have an exceptionally large second hyperpolarizability. Thus, the considered set of Ni dithiolene derivatives is likely to have applications in the development of photonic devices.

The electronic contribution to the components of the static polarizability and second hyperpolarizability of Li2 is studied using SCF, MP2 and MP4[SDTQ] theories with several large basis sets. The computed polarizability is within the experimental error limits. The static vibrational contributions to these properties are also determined. The nuclear motion has a considerable effect on the second hyperpolarizability but not on the polarizability.

The electronic ground state, stability, and linear and nonlinear optical properties of HXeOXeF and FXeOXeF have been studied theoretically by employing complete active space valence bond (CASVB), multistate complete active space perturbation theory (MS-CASPT2), and coupled cluster methods. It is shown that the oxygen inserted between the two Xe atoms significantly modifies the ground-state electronic configuration of the formed derivative by increasing the closed-shell contribution (σ(2)) and removing the diradicaloid character observed in HXe(2)F. The electronic charge distribution has been analyzed by employing the atoms-in-molecules (AIM) method. The dissociation channels of HXeOXeF and FXeOXeF have been studied in detail. It was found that these compounds are metastable, protected by substantial energy barriers and, thus, they can be prepared under appropriate conditions. Both two- and three-body dissociation reactions have been considered. The effects of inserting O in HXe(2)F and substituting H (HXeOXeF) by F, leading to FXeOXeF, on the energy barriers are discussed. The significant effects of the inserted oxygen on the polarizability and even more on the first hyperpolarizability have been computed and rationalized.

We report the partitioning of the interaction-induced static electronic dipole (hyper)polarizabilities for linear hydrogen cyanide complexes into contributions arising from various interaction energy terms. We analyzed the nonadditivities of the studied properties and used these data to predict the electric properties of an infinite chain. The interaction-induced static electric dipole properties and their nonadditivities were analyzed using an approach based on numerical differentiation of the interaction energy components estimated in an external electric field. These were obtained using the hybrid variational-perturbational interaction energy decomposition scheme, augmented with coupled-cluster calculations, with singles, doubles, and noniterative triples. Our results indicate that the interaction-induced dipole moments and polarizabilities are primarily electrostatic in nature; however, the composition of the interaction hyperpolarizabilities is much more complex. The overlap effects substantially quench the contributions due to electrostatic interactions, and therefore, the major components are due to the induction and exchange-induction terms, as well as the intramolecular electron-correlation corrections. A particularly intriguing observation is that the interaction first hyperpolarizability in the studied systems not only is much larger than the corresponding sum of monomer properties, but also has the opposite sign. We show that this effect can be viewed as a direct consequence of hydrogen-bonding interactions that lead to a decrease of the hyperpolarizability of the proton acceptor and an increase of the hyperpolarizability of the proton donor. In the case of the first hyperpolarizability, we also observed the largest nonadditivity of interaction properties (nearly 17%) which further enhances the effects of pairwise interactions.

The potential energy surface (PES) of Ti@C(28) has been revisited, and the stationary points have been carefully characterized. In particular, the C(2v) symmetry structure considered previously turns out to be a transition state lying 2.3 kcal/mol above the ground state of C(3v) symmetry at the MP2/6-31G(d) level. A large binding energy of 181.3 kcal/mol is found at the ROMP2/6-31G(d) level. Topological analysis of the generalized Ti@C(28) density reveals four bond paths between Ti and carbon atoms of the host. The character of all four contacts corresponds to a partially covalent closed shell interaction. UV-vis, IR, and Raman spectra are calculated and compared with C(28)H(4). The dipole moment and the static electronic and double harmonic vibrational (hyper)polarizabilities have been obtained. Distortion of the fullerene cage due to encapsulation leads to nonzero diagonal components of the electronic first hyperpolarizability β, and to an increase in the diagonal components of the electronic polarizability α and second hyperpolarizability γ. However, introduction of the Ti atom causes a comparable or larger reduction in most cases due to localized bonding interactions. At the double harmonic level, the average vibrational β is much larger than its electronic counterpart, but the opposite is true for α and for the contribution to γ that has been calculated. There is also a very large anharmonic (nuclear relaxation) contribution to β which results from a shallow PES with four minima separated by very low barriers. Thus, the vibrational γ (and α) may, likewise, become much larger when anharmonicity is taken into account.

In the present study we report on the linear and nonlinear optical properties of C(60)-triphenylamine (TPhA) hybrids. The synthesized materials were prepared following the 1,3-dipolar cycloaddition of azomethine ylides onto the skeleton of C(60) forming the TPhA-based monoadduct, equatorial bis-adduct and dumbell C(60). Complementary spectroscopic techniques, such as NMR, MALDI-TOF-MS, and ATR-IR are applied for the structural characterization of the hybrid materials, while intermolecular electronic interactions are investigated by UV-Vis measurements. In all considered cases, C(60) serves as an acceptor while the triphenylamine unit is chosen as a donor. In order to investigate the dependence of the second-order hyperpolarizability on the architecture of the systems (D-A, A-D-A) we use a Z-scan technique employing 532 nm, 35 ps laser pulses. We have found that the total second-order hyperpolarizability of the C(60)-TphA-C(60) system is several times larger than that of TPhA-C(60). The results of experimental measurements are supported by quantum-chemical calculations.

Using a wide variety of quantum-chemical methods we have analyzed in detail the linear and non-linear optical properties of [60]fullerene-chromophore dyads of different electron-donor character. The dyads are composed of [60]fullerene covalently linked with 2,1,3-benzothiadiazole and carbazole derivatives. Linear scaling calculations of molecular (hyper)polarizabilities were performed using wave function theory as well as density functional theory (DFT). Within the former approach, we used both semiempirical (PM3) and ab initio (Hartree-Fock and second-order Møller-Plesset perturbation theory) methods. Within the latter approach only the recently proposed long-range (LRC) schemes successfully avoid a large overshoot in the value obtained for the first hyperpolarizability (β). Calculations on model fullerene derivatives establish a connection between this overshoot and the electron-donating capability of the substituent. Substitution of 2,1,3-benzothiadiazole by the triphenylamine group significantly increases the electronic first and second hyperpolarizabilities as well as the two-photon absorption cross section. For [60]fullerene-chromophore dyads we have, additionally, observed that the double harmonic vibrational contribution to the static beta is much larger than its electronic counterpart. The same is true for the dc-Pockels β as compared to the static electronic value, although the vibrational term is reduced in magnitude; for the intensity-dependent refractive index the vibrational and electronic terms are comparable. A nuclear relaxation treatment of vibrational anharmonicity for a model fulleropyrrolidine molecule yields a first-order contribution that is substantially more important than the double harmonic term for the static β.

The equilibrium geometry, energy, dipole polarizability, and second hyperpolarizability of the rhombic B4 -cluster with D2h symmetry are calculated by restricted (RHF) and unrestricted (UHF) Hartree-Fock theory; Moller-Plesset perturbation theory (MPn); coupled-cluster theory with singles, doubles, and a perturbational treatment for connected triples [CCSD(T)]; Brueckner doubles with a perturbational treatment for connected triples [BD(T)]; and complete active space SCF (CASSCF) and restricted active space SCF (RASSCF) methods, using three different basis sets. The multireference methods show that excited state configurations contribute appreciably to the ground state wave function. Accordingly, the RHF method yields results that differ greatly from those of the correlated methods, even for the geometry. UHF gives more reliable geometries, but suffers from high spin contamination. The electric properties calculated at reasonably highly correlated levels are qualitatively comparable for both the single reference and multireference descriptions, although differences between CCSD(T) and BD(T) are larger than usually reported in the literature and properties calculated at the MPn (n=2, 3, 4) series show much damped oscillatory behavior, especially for the components along the long in-plane axis. It is found that inclusion of f-functions in the basis set do not have a large effect on the electric properties. ©1999 John Wiley & Sons, Inc. J Comput Chem 20: 679-687, 1999.

The dipole moments μ, polarizabilities α, and first and second hyperpolarizabilities, β and γ of LiH, NaH and KH (MeH) have been computed using Hartree-Fock, MP2 and CCSD(T) theories. The static electronic and vibrational contributions to these properties are presented. The vibrational properties have been analysed into contributions due to zero-point vibrational averaging and pure vibrational terms. An alternative dissection of the vibrational properties into nuclear relaxation and curvature terms has also been considered. KH has been selected as a model system to study how the number of electrons, which are correlated (2, 10 and 20) affect both electronic and vibrational properties. The 10 electron approximation gives results that are practically the same as those computed by taking into account all 20 electrons of KH. The double-harmonic approximation has been shown to give satisfactory results for the pure vibrational contributions to the polarizability and the first hyperpolarizability, while this ap...

Static and dynamic polarizabilities and second hyperpolarizabilities are presented for ethylene, including electronic, pure vibrational and zero-point vibrational averaging (ZPVA) contributions. Static pure vibrational hyperpolarizabilities are of commensurate size with their electronic counterparts but show less dependence on basis set and (MP2) electron correlation. A Hartree–Fock estimate for the static ZPVA correction to γ is found to be 10% of the corresponding electronic contribution. The dynamic pure vibrational hyperpolarizability, despite being significant for the optical Kerr effect and intensity-dependent refractive index, reduces in magnitude for second and third harmonic generation, leaving ZPVA as the dominant vibrational effect.

The 3-aminoacroleine molecule is used as a model to study the dependence of linear and nonlinear molecular electric properties on the molecular conformation. Among four conformers of this molecule one of them has the intramolecular hydrogen bond, and thus, permits the study of its effect on electric properties. It has been established on the basis of MP2 calculations that the most elongated conformer of 3-aminoacroleine has the largest values of the dipole moment, dipole polarizability, and first hyperpolarizability. They were found to significantly depend on the conformation of the molecule. Also the electron correlation effect on the first hyperpolarizability is found to be very large. The results calculated for four conformers permit also to estimate the effect of the intramolecular hydrogen bond. The incremental lowering of the dipole polarizability is negligible whereas that for the first hyperpolarizability is of the order of −120 a.u. Considerable attention has been paid to the calculation of vibration corrections to electric properties. For the dipole polarizability and first hyperpolarizability the so-called pure vibrational corrections are found to be unusually large. These large values arise from the use of the harmonic zeroth-order approximation in the perturbation treatment of contributions due low-frequency modes. It is concluded that the perturbation method for the evaluation of pure vibrational corrections to electric properties should be used with great care and possibly preceded by the analysis of low frequency modes.

The polarizability (α) and the second hyperpolarizability (γ) of tetrakis(phenylethynyl)ethene (TPEE) are compared and analyzed in connection with the properties (α, γ) of a series of selected/designed molecules having different conjugation patterns. Several lithiated derivatives of TPEE are designed and shown to have very enhanced second hyperpolarizabilities; for example, one of the lithiated TPEE has a 1.6×103 times larger second hyperpolarizability than that of benzene. The potential of the proposed derivatives for applications in photonics is noted. The polarizabilities and the hyperpolarizabilities of the considered molecules have been computed employing the PM3 method which has been proven to be adequate for the present comparative study. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 72: 177–187, 1999

A series of novel [60]fullerene-ferrocene and [60]fullerene-porphyrin dyads, in which a fullerene and an electron donating moiety are attached through a flexible triethylene glycol linker are synthesized and their nonlinear optical (NLO) response studied. Specifically the third-order susceptibility chi((3)) of all fullerene derivatives are measured in toluene solutions by the optical Kerr effect (OKE) technique using 532 nm, 35 ps laser pulses and their second hyperpolarizability gamma are determined. All fullerene dyads studied exhibit enhancement of their NLO response compared to pristine fullerenes which has been attributed to the formation of a charge separated state. All experimentally measured hyperpolarizability gamma values are also calculated by the semiempirical methods AM1 and PM3. A good correlation is found between the theoretical and experimental values, suggesting that simple semi-empirical methods can be employed for the designing and optimization of the fullerene-containing dyads displaying improved nonlinear responses.

Geometries, inversion barriers, static and dynamic electronic and vibrational dipole polarizability (alpha), and first (beta) and second (gamma) hyperpolarizability of the pyrrole homologues C(4)H(4)XH (X = N, P, As, Sb, Bi) have been calculated by Hartree-Fock, Møller-Plesset second-order perturbation theory, coupled-cluster theory accounting for singles, doubles, and noniterative triple excitations methods, as well as density functional theory using B3LYP and PBE1PBE functionals and Sadlej's Pol and 6-311G basis sets. Relativistic effects on the heavier homologues stibole and bismole have been taken into account within effective core potential approximation. The results show that the electronic (hyper)polarizabilities monotonically increase with the atomic number of the heteroatom, consistent with the decrease in the molecular hardness. Ring planarization reduces the carbon-carbon bond length alternation of the cis-butadienic unit, enhancing the electronic polarizability values (alpha(e)) by 4-12% and the (hyper)polarizability values (and gamma(e)) by 30-90%. Pure vibrational and zero-point vibrational average contributions to the (hyper)polarizabilities have been determined within the clamped nucleus approach. In the static limit, the pure vibrational hyperpolarizabilities have a major contribution. Anharmonic corrections dominate the pure vibrational hyperpolarizabilities of pyrrole, while they are less important for the heavier homologues. Static and dynamic electronic response properties of the pyrrole homologues are comparable to or larger than the corresponding properties of the furan and cyclopentadiene homologue series.

The polarizability and first and second hyperpolarizabilities of several 4,4'-disubstituted trans- stilbene (tSB) derivatives, which include the NO2 group as an acceptor (A) and several lithium containing donors (D) have been computed. Ab initio theory using a 6-31G basis set at the SCF and MP2 levels has been sued to optimize the structure of tSB and the disubstituted derivative which includes the NO2 (A) and the NLi2 (D). Their polarizabilities and hyperpolarizabilities have also been computed at the SCF level. MP2 theory has been used to assess the effect of correlation on the largest polarizability and second hyperpolarizability components of the above compounds. The preset results, together with our recent work show that the second hyperpolarizabilities of some lithiated derivatives depend quite a lot on the molecular geometries and lithiation leads to a big increase of the hyperpolarizabilities of the resulting derivatives. This finding suggests that at lest some of the lithiated derivatives are very likely to be useful for non-linear optical applications.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

In this study we report on the electronic and vibrational (hyper)polarizabilities of donor–acceptorsubstituted azobenzene. It is observed that both electronic and vibrational contributions to the electric dipole first hyperpolarizability of investigated photoactive molecule substantially depend on the conformation. The contributions to the nuclear relaxation first hyperpolarizability are found to be quite important in the case of two considered isomers (cis and trans). Although the double-harmonic term is found to be the largest in terms of magnitude, it is shown that the total value of the nuclear relaxation contribution to vibrational first hyperpolarizability is a result of subtle interplay of higher-order contributions. As a part of the study, we also assess the performance of long-range-corrected density functional theory in determining vibrational contributions to electric dipole (hyper)polarizabilities. In most cases, the applied long-range-corrected exchange correlation potentials amend the drawbacks of their conventional counterparts

The dipole moment, parallel dipole polarizability, and the parallel first hyperpolarizability of the coinage metal hydrides (CuH, AgH, AuH) are studied in the context of their vibrational contributions. The partition of the property values into pure electronic, vibrational averaging, and pure vibrational terms is discussed, and the corresponding contributions are calculated by means of the field-dependent Numerov–Cooley integration technique. The potential energy and property surfaces, required for the evaluation of these contributions, follow from different high-level electronic structure calculations. Parallel to the nonrelativistic studies, a relativistic treatment of the investigated properties has been carried out. It has been found that relativistic effects significantly reduce the magnitude of the vibrational corrections to the studied properties. A particularly large relativistic reduction has been found for the vibrational contribution to the first hyperpolarizability. The relativistic effect is enhanced with increasing nuclear charge of the heavy atom, and can be interpreted in terms of the relativistic effect on the potential energy and electric property curves.

Vibrational contributions to the dipole polarizabilities and hyperpolarizabilities of cyclopropenone and cyclopropenethione are reported. Simultaneous calculations have been carried out for the respective saturated and noncyclic counterparts of these molecules. The results have been analyzed and interpreted in terms of different structural and electronic features of the studied molecules: i.e., the oxygen–sulfur replacement, the saturation of the carbon ring, and the removal of the intramolecular strain. For static dipole polarizabilities the vibrational contribution computed at the molecular equilibrium geometry can account for more than 10% of the total value for a given component of the tensor. Both the zero-point vibrational average and pure vibrational terms are important for most of the studied molecules. In the case of the first dipole hyperpolarizability the total vibrational correction is dominated by the pure vibrational term. The vibrational corrections to dipole polarizabilities show certain regularities which can be interpreted in terms of the electronic structure of the investigated molecules. Much less clear is the pattern of behavior for the first dipole hyperpolarizability. It has been found, however, that the analysis of these data is greatly facilitated by the separate consideration of the nuclear relaxation and curvature terms. Limited study of the frequency dependence of the calculated vibrational corrections shows that in the case of the dipole polarizability, they are almost quenched to zero. In contrast, at nonzero frequencies, the vibrational contribution to the first dipole hyperpolarizability tensor β(−ω;ω,0), which determines the so-called electro-optic Pockels effect, can be as important as the pure electronic term.

We report the results of coupled Hartree-Fock computations for the average polarizability, α, and hyperpolarizability, γ, of CH4, C2H6, C3H6 and C3H8. The Hamiltonian matrices are constructed from an extended CNDO model. Small as well as large basis sets were tested. Agreement with available experimental values is within 13% for α and 31% for γ.

We report the results of calculations of the average polarizability α and second hyperpolarizability γ for benzene, naphthalene, and three different configurations of biphenyl, phenanthrene, anthracene, and pyrene. The computations were performed employing a scheme whose main elements are McWeeny’s coupled Hartree–Fock perturbation theory, the CNDO approximations, and a small, properly optimized, extended basis. The mean error for the average polarizabilities is 7%. The error for the second hyperpolarizability of naphthalene is within the experimental uncertainty.

The polarizability, α, and second hyperpolarizability, γ, of the phenyl cation are computed by employing the CHF-PT-EB-CNDO method. Variations of the properties induced by changes in the structure of the cation are discussed.

The average polarizability and second hyperpolarizability of some azabenzenes are reported and interpreted. A rule allowing the development of basis sets for complex molecules from those of appropriately defined fragments or models of them has been proposed and successfully tested.

The average polarizability and second hyperpolarizability of some azabenzenes are reported and interpreted. A rule allowing the development of basis sets for complex molecules from those of appropriately defined fragments or models of them has been proposed and successfully tested.

The preparation of the first soluble quaterrylene derivative featuring peripheral tert-butyl substituents and sterically hindering, core-anchored triflate groups has been achieved. This involves a facile synthetic route based on an oxidative coupling of perylene precursors in the presence of H2O2 as oxidant. The steric hindrance between the OTf substituents at the central bay position of the quaterrylene board triggers a strong deformation of the central perylene planarity, which forces the quaterrylene platform to adopt a twisted geometry as shown by X-Ray analysis. Exceptionally, photophysical investigations show that the core-twisted quaterrylene phosphoresces in the NIR spectral region at 1716 nm. Moreover, third-order nonlinear optical (NLO) measurments on solutions and thin film containing the relevant molecule showed very large second hyperpolarizability values, as predicted by theoretical calculations at the CAM-B3LYP/6-31G** level of theory, making this material very appealing for photonic applications. This article is protected by copyright. All rights reserved.