Non-nearest Neighbor Interactions Research Articles

Structure-property relationships in alkoxy substituted benzoates from experimental and computational thermochemistry

The energetics of formation and the phase transitions for isomeric methyl and ethyl methoxy‑benzoates were studied. The vapour pressures of methyl 2‑methoxy-benzoate and methyl 4‑methoxy-benzoate were measured by transpiration method. The high-precision combustion calorimetry was used to derive the liquid-phase enthalpy of formation of methyl 2‑methoxy-benzoate. The new results and the data available in the literature were critically evaluated using the structure-property correlations. Reliable correlations were established between the vaporisation enthalpies and the normal boiling temperatures as well as with the Kovats indices. Moreover, the validity of vaporisation enthalpies of alkyl methoxy‑benzoates was proved using structure-property relationships within families of structurally similar molecules. Mutual validation of the experimental and theoretical gas phase enthalpies of formation was performed using high-level quantum-chemical methods. The enthalpic contributions to the enthalpy of formation in the gas phase, resulting from the nearest and non-nearest neighbour interactions of the substituents in the benzene ring, were developed and used to quantify the intra-molecular hydrogen bond strength in the ortho-substituted species.

Ab Initio Group Additive Values for Thermodynamic Carbenium Ion Property Prediction

Carbenium ions are important intermediates in both zeolite and plasma chemistry. The construction of kinetic models for zeolite and plasma chemistry requires the incorporation of thermodynamic properties of these carbenium ions. In this way, thermodynamic equilibrium is incorporated resulting in more accurate and general kinetic models, which facilitate rational zeolite design and plasma process development. In this work, a consistent set of 46 group additive values (GAVs) and non-nearest neighbor interactions (NNIs) is determined for the standard enthalpy of formation, standard molar entropy, and heat capacity. The GAVs are regressed based on 165 quantum chemistry calculations with the CBS-QB3 composite method for carbenium ions as CBS-QB3 was proven a valid method for carbenium property prediction. The presented group additive approach gives the first GAVs and NNIs for entropy and heat capacity and 33 novel values for enthalpy prediction. The determined non-nearest neighbor interactions account for the effect of longer range hyperconjugation, resonance stabilization, and inductive stabilization, which are shown to be crucial for the carbenium stability. The presented group additivity scheme ensures an accurate prediction of all properties with a mean absolute error of 4.82 kJ/mol, 4.92 J/(mol·K), and 1.95 J/(mol·K) for the standard enthalpy of formation, standard molar entropy, and heat capacity, respectively. The reported GAVs and NNIs ensure the thermodynamic property prediction of paraffinic, olefinic, alkynic, aromatic, and five- and six-ring naphthenic cations.

Thermodynamic properties of some isomeric 5-(nitrophenyl)-furyl-2 derivatives

BackgroundThe aim of the current work was to determine thermodynamical properties of 5-(nitrophenyl)-2-furaldehyde oximes and 3-[5-(nitrolphenyl)-2-furyl]acrylic acids.ResultsThe temperature dependences of saturated vapor pressures of 5-(nitrophenyl)-2-furaldehyde oximes and 3-[5-(nitrolphenyl)-2-furyl]acrylic acids were determined by the Knudsen effusion method. The results are presented by the Clapeyron–Clausius equation in linear form, and via this form, the standard enthalpies of sublimation of compounds were calculated at 298.15 K. The standard molar formation enthalpies of compounds in crystalline state at 298.15 K were determined indirectly from the corresponding standard molar combustion enthalpy, obtained using combustion bomb calorimetry. The non-nearest neighbour interactions (strain) in molecule were defined. The ideal-gas enthalpies of investigated compounds formation and the data available from the literature were used for calculation of group-additivity parameters and the correction terms useful in the application of the Benson correlation.ConclusionDetermining the thermodynamic properties for these compounds will contribute to solving practical problems pertaining to optimization processes of their synthesis, purification and application. It will also provide a more thorough insight regarding the theoretical knowledge of their nature and are necessary for the application of the Benson group-contribution correlation for calculation of Delta {}_{f}H_{{m(298.15{text{K}})}}^{o} (g)calc.

Unified nonlocal rational continuum models developed from discrete atomistic equations

In this paper, a unified nonlocal rational continuum enrichment technique is presented for improving the dispersive characteristics of some well known classical continuum equations on the basis of atomistic dispersion relations. This type of enrichment can be useful in a wide range of mechanical problems such as localization of strain and damage in many quasibrittle structures, size effects in microscale elastoplasticity, and multiscale modeling of materials. A novel technique of transforming a discrete differential expression into an exact equivalent rational continuum derivative form is developed considering the Taylor’s series transformation of the continuous field variables and traveling wave type of solutions for both the discrete and continuum field variables. An exact equivalent continuum rod representation of the 1D harmonic lattice with the non-nearest neighbor interactions is developed considering the lattice details. Using similar enrichment technique in the variational framework, other useful higher-order equations, namely nonlocal rational Mindlin–Herrmann rod and nonlocal rational Timoshenko beam equations, are developed to explore their nonlocal properties in general. Some analytical and numerical studies on the high frequency dynamic behavior of these novel nonlocal rational continuum models are presented with their comparison with the atomistic solutions for the respective physical systems. These enriched rational continuum equations have crucial use in studying high-frequency dynamics of many nano-electro-mechanical sensors and devices, dynamics of phononic metamaterials, and wave propagation in composite structures. These new models can help to circumvent the biggest problem regarding size and time restrictions in many atomistic simulations.

Influence of two bulge loops on the stability of RNA duplexes.

Fifty-three RNA duplexes containing two single nucleotide bulge loops were optically melted in 1 M NaCl in order to determine the thermodynamic parameters ΔH°, ΔS°, ΔG°37, and TM for each duplex. Because of the large number of possible combinations and lack of sequence effects observed previously, we limited our initial investigation to adenosine bulges, the most common naturally occurring bulge. For example, the following duplexes were investigated: 5′GGCAXYAGGC/3′CCG YX CCG, 5′GGCAXY GCC/3′CCG YXACGG, and 5′GGC XYAGCC/3′CCGAYX CGG. The identity of XY (where XY are Watson–Crick base pairs) and the total number of base pairs in the terminal and central stems were varied. As observed for duplexes with a single bulge loop, the effect of the two bulge loops on duplex stability is primarily influenced by non-nearest neighbor interactions. In particular, the stability of the stems influences the destabilization of the duplex by the inserted bulge loops. The model proposed to predict the influence of multiple bulge loops on duplex stability suggests that the destabilization of each bulge is related to the stability of the adjacent stems. A database of RNA secondary structures was examined to determine the naturally occurring abundance of duplexes containing multiple bulge loops. Of the 2000 examples found in the database, over 65% of the two bulge loops occur within 3 base pairs of each other. A database of RNA three-dimensional structures was examined to determine the structure of duplexes containing two single nucleotide bulge loops. The structures of the bulge loops are described.

First‐principles based group additivity values for thermochemical properties of substituted aromatic compounds

A set of 7 Benson group additive values (GAV) together with 15 correction terms for non‐nearest neighbor interactions (NNI) is developed to calculate the gas phase standard enthalpies of formation, entropies and heat capacities of monocyclic aromatic compounds containing methyl, ethyl, vinyl, formyl, hydroxyl, and methoxy substituents. These GAVs are obtained through least squares regression of a database of thermodynamic properties of 143 molecules, calculated at the post‐Hartree–Fock G4 composite method. Out of the 15 NNIs, which account for several well‐known substituent effects in aromatic molecules, 13 have been determined for the first time. All but two group additively calculated standard enthalpies of formation agree within 4 kJ mol−1. The entropies and the heat capacities generally deviate less than 4 J mol−1 K−1 from the ab initio results. Natural bond orbital analysis is utilized to identify the underlying causes of the observed NNIs. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3858–3870, 2015

Minimizers with Bounded Action for the High-Dimensional Frenkel–Kontorova Model

In Aubry–Mather theory for monotone twist maps or for one-dimensional Frenkel–Kontorova (FK) model with nearest neighbor interactions, each global minimizer (minimal energy configuration) is naturally Birkhoff. However, this is not true for the one-dimensional FK model with non-nearest neighbor interactions or for the high-dimensional FK model. In this paper, we study the Birkhoff property of minimizers with bounded action for the high-dimensional FK model.

Group Additive Values for the Gas‐Phase Standard Enthalpy of Formation, Entropy and Heat Capacity of Oxygenates

A complete and consistent set of 60 Benson group additive values (GAVs) for oxygenate molecules and 97 GAVs for oxygenate radicals is provided, which allow to describe their standard enthalpies of formation, entropies and heat capacities. Approximately half of the GAVs for oxygenate molecules and the majority of the GAVs for oxygenate radicals have not been reported before. The values are derived from an extensive and accurate database of thermochemical data obtained by ab initio calculations at the CBS-QB3 level of theory for 202 molecules and 248 radicals. These compounds include saturated and unsaturated, α- and β-branched, mono- and bifunctional oxygenates. Internal rotations were accounted for by using one-dimensional hindered rotor corrections. The accuracy of the database was further improved by adding bond additive corrections to the CBS-QB3 standard enthalpies of formation. Furthermore, 14 corrections for non-nearest-neighbor interactions (NNI) were introduced for molecules and 12 for radicals. The validity of the constructed group additive model was established by comparing the predicted values with both ab initio calculated values and experimental data for oxygenates and oxygenate radicals. The group additive method predicts standard enthalpies of formation, entropies, and heat capacities with chemical accuracy, respectively, within 4 kJ mol(-1) and 4 J mol(-1) K(-1) for both ab initio calculated and experimental values. As an alternative, the hydrogen bond increment (HBI) method developed by Lay et al. (T. H. Lay, J. W. Bozzelli, A. M. Dean, E. R. Ritter, J. Phys. Chem.- 1995, 99, 14514) was used to introduce 77 new HBI structures and to calculate their thermodynamic parameters (Δ(f)H°, S°, C(p)°). The GAVs reported in this work can be reliably used for the prediction of thermochemical data for large oxygenate compounds, combining rapid prediction with wide-ranging application.

KAM theory for quasi-periodic equilibria in 1D quasi-periodic media: II. Long-range interactions

We consider Frenkel–Kontorova models corresponding to one-dimensional quasi-crystal with non-nearest neighbor and many-body interactions. We formulate and prove a KAM type theorem which establishes the existence of quasi-periodic solutions. The interactions we consider do not need to be of finite range or involve finitely many particles, but have to decay sufficiently fast with respect to the distance of the position of the atoms. The KAM theorem we present has an a posteriori format. We do not need to assume that the system is close to integrable. We just assume that there is an approximate solution for the functional equation which satisfies some non-degeneracy conditions.

Travelling waves in discrete nonlinear systems with non-nearest neighbour interactions

The aim of this paper is to provide a construction of travelling waves in an extended one-dimensional lattice model with non-nearest neighbour interactions. These models, coming mainly from solid state physics, are known to play an important role in the mechanisms of propagation of energy. We focus on an extended version of the Klein–Gordon chains, i.e. each particle is embedded into an an-harmonic potential and linearly coupled to their first and second neighbours. We use the technique of reduction to a finite-dimensional centre manifold to prove the existence of travelling waves of several types and investigate the role played by the interaction to second nearest neighbours.

Excitonic versus electronic couplings in molecular assemblies: The importance of non-nearest neighbor interactions

We demonstrate that for a range of phenylene- and thiophene-based conjugated polymers of practical relevance for optoelectronic applications, exciton couplings in one-dimensional stacks deviate significantly from the nearest neighbor approximation. Instead, long-range interactions with non-nearest neighbors have to be included, which become increasingly important with growing oligomer size. While the exciton coupling vanishes for infinitely long ideal polymer chains and provides a sensitive measure of the actual conjugation length, the electronic coupling mediating charge transport shows rapid convergence with molecular size. Similar results have been obtained for very different molecular backbones, thus highlighting the general character of these findings.

Higher order interactions in magneto-inductive waveguides

The properties of periodic chains of magnetically coupled L–C resonators supporting magneto-inductive (MI) waves are examined in the case when non-nearest neighbour interactions are significant. The variation of the coupling coefficient with separation is measured using resonant elements based on printed circuit board inductors and surface mount capacitors, and used to predict the S-parameters and dispersion characteristics of magnetoinductive waveguides. Good agreement with experimental measurements is obtained when higher order interactions are included. The significance of non-nearest neighbour interactions in more general MI wave devices is then highlighted in an example problem involving reflection from a waveguide discontinuity, and the influence of higher order evanescent waves is discussed.

Prediction of Enthalpy of Formation in the Solid State (at 298.15K) Using Second-Order Group Contributions—Part 2: Carbon-Hydrogen, Carbon-Hydrogen-Oxygen, and Carbon-Hydrogen-Nitrogen-Oxygen Compounds

A program has been undertaken to develop a new group contribution method, based on Benson’s group additivity technique, estimate as precisely as possible solid state enthalpies of formation, at 298.15K, of C–H compounds, C–H–O compounds, and C–H–N–O compounds. A set of 1017 experimental values of the enthalpy of formation has been studied and compared to the predicted values of this new method as well as the method of Domalski and Hearing. This new estimation technique leads to a higher precision and reliability. With the inclusion of additional group values, a wider range of compounds can be studied (compared to the Domalski and Hearing technique). Comparison with a quantum mechanical method [Rice et al., Combust. Flame 118, 445 (1999)] shows that the list of group contribution values, ring strain corrections, and non-nearest neighbor interactions provided here yields better estimates overall.

Prediction of Enthalpy of Formation in the Solid State (at 298.15K) using Second-Order Group Contributions. Part 1. Carbon-Hydrogen and Carbon-Hydrogen-Oxygen Compounds

A predictive method, based on Benson’s group additivity technique, is developed for calculating the enthalpy of formation in the solid phase, at 298.15K, of carbon-hydrogen compounds and carbon-hydrogen-oxygen compounds. A complete database compiles 398 experimental enthalpies of formation. The whole group contribution values, ring strain corrections, and nonnearest neighbor interactions evaluated are listed. Finally a comparison with Cohen’s method indicates that this new estimation method leads to higher precision and reliability.

On the influence of non‐nearest neighbor interactions and anharmonicity on the atomic properties of a crystal surface: one‐dimensional model

AbstractWe describe self‐consistently the effects of non‐nearest neighbor interactions and anharmonicity on the atomic properties of a crystal surface. An approach is developed based on the unsymmetrized self‐consistent field approximation (USF). The structural dynamical and thermodynamic properties of a semi‐infinite linear chain are studied in the classical limit. Expressions for the lattice relaxation in the vicinity of the surface the mean‐squared atomic displacements and for the surface energy and free energy are obtained. Quantitative estimates were made using the Lennard–Jones 6–12 interatomic potential.

One-dimensional J-aggregates: Dependence of the properties of the exciton band on the model of the intermolecular coupling

The spectral properties of one-dimensional thiacarbocyanine dye aggregates were simulated by the combination of exciton interaction with a diagonal energetic disorder. Contrary to previous models incorporating disorder, the exciton interaction was calculated using the transition densities obtained form PPP-wave functions and interactions between all molecules were considered. The effects of the aggregate size, non-nearest neighbor interactions, diagonal disorder and to some extent exciton phonon coupling on the spectral position of the maxima, the FWHM of the spectra and the superradiance are investigated for H- and J-aggregates at 298 and 20 K. At 298 K the experimental properties of H-aggregates and J-aggregates of 3,3 ′-disulfopropyl-5,5 ′-dichloro-carbocyanine with 1 molecule per unit cell are compared to the simulations.

The electronic band structure of polydiacetylenes with second- and third-neighbor hopping interaction

We have studied the energy band structure of polydiacetylenes (PDAs) using the extensional Hückel Hamiltonian that includes the nonnearest-neighbor hopping interactions. The results show that with increase in the nonnearest-neighbor hopping interaction parameters ρ1 and ρ2, (i) the energy band symmetry is broken and the energy gap 2Δ has changed, (ii) the locations and the widths of energy bands have changed and their shifts depend mainly on ρ1 (next-neighbor hopping interactions), and (iii) the energy gap 2Δ depends mainly on ρ2 (third-neighbor hopping interactions), the effects of the nonnearest-neighbor hopping interaction on the band structure are discussed. PACS No.: 31.15Ct

Thermochemical Studies for Determination of the Standard Molar Enthalpies of Formation of Alkyl-Substituted Furans and Some Ethers

The standard molar enthalpies of vaporization Δ l g H m o of 2,5-dimethylfuran, 2-tert-butylfuran, 2,5-di-tert-butylfuran, cyclopentenyl methyl ether, cyclohexenyl methyl ether, and tert-amyl methyl ether were obtained from the temperature variation of the vapor pressure measured in a flow system. The standard (p° = 0.1 MPa) molar enthalpies of formation Δf H m o (1) at the temperature T = 298.15 K were measured using combustion calorimetry for 2,5-dimethylfuran, 2-tert-butylfuran, and 2,5-di-tert-butylfuran. From the derived standard molar enthalpies of formation for gaseous compounds, ring correction terms and non-nearest neighbor interactions useful in the application of the Benson group additivity scheme were calculated.

Revised Group Additivity Values for Enthalpies of Formation (at 298 K) of Carbon–Hydrogen and Carbon–Hydrogen–Oxygen Compounds

A program has been undertaken for the evaluation and revision of group additivity values (GAVs) necessary for predicting, by means of Benson’s group additivity method, thermochemical properties of organic molecules. This review reports on the portion of that program dealing with GAVs for enthalpies of formation at 298.15 K (hereinafter abbreviated as 298 K) for carbon–hydrogen and carbon–hydrogen–oxygen compounds. A complete database of experimental data for gas, liquid, and crystal (solid) phase enthalpies of formation is presented. The GAVs, ring strain corrections, and non-nearest neighbor interactions derived from the database are presented in tabular form, together with a description of their evaluation and comments on reliability, uncertainties, and missing or questionable data.

Weak interactions in extended HCN chains

Model calculations have been carried out on extended linear chains of up to 50 HCN molecules in order to assess the effects of pairwise versus non-pairwise intermolecular interactions. The contraction in separation distance from the dimer to the infinite chain crystalline structure is known to be 0.08–0.10 Å. Pairwise interactions lead to a share of this contraction as non-nearest neighbor interactions take effect. Direct polarization, a three-body interaction, adds the bulk of the remaining contraction, and full treatment of back polarization yields a net contraction of 0.076 Å. Threebody multipole dispersion will also contribute to the contraction. The per monomer dipole moment grows by 0.8 Debye because of mutual polarization in the longest chain studied.