The hydrogen bond is the most important of all directional intermolecular interactions. It is operative in determining molecular conformation, molecular aggregation, and the function of a vast number of chemical systems ranging from inorganic to biological. Research into hydrogen bonds experienced a stagnant period in the 1980s, but re-opened around 1990, and has been in rapid development since then. In terms of modern concepts, the hydrogen bond is understood as a very broad phenomenon, and it is accepted that there are open borders to other effects. There are dozens of different types of X-H.A hydrogen bonds that occur commonly in the condensed phases, and in addition there are innumerable less common ones. Dissociation energies span more than two orders of magnitude (about 0.2-40 kcal mol(-1)). Within this range, the nature of the interaction is not constant, but its electrostatic, covalent, and dispersion contributions vary in their relative weights. The hydrogen bond has broad transition regions that merge continuously with the covalent bond, the van der Waals interaction, the ionic interaction, and also the cation-pi interaction. All hydrogen bonds can be considered as incipient proton transfer reactions, and for strong hydrogen bonds, this reaction can be in a very advanced state. In this review, a coherent survey is given on all these matters.

The hydrogen bond in the solid state.

Structure, energetics, and dynamics of the nucleic Acid base pairs: nonempirical ab initio calculations.

Molecular Clusters of π-Systems: Theoretical Studies of Structures, Spectra, and Origin of Interaction Energies

Ab initio calculations are used to analyze the CH···O interaction between FnH3-nCH as proton donor and H2O, CH3OH, and H2CO as acceptor. The interaction is quite weak with CH4 as donor but is enhanced by 1 kcal/mol with each F added to the donor. The CH···O interaction behaves very much like a conventional OH···O H-bond in most respects, including shifts in electron density that accompany the formation of the bond and the magnitudes of the various components of the interaction energy. The two sorts of H-bonds also gravitate toward a similar equilibrium geometry and are comparably sensitive to deformations from that structure. In a quantitative sense, while both CH···O and OH···O prefer a linear configuration, the former is somewhat more easily bent and is less sensitive to stretches from its equilibrium H-bond length. Whereas the OH bond has been shown to stretch and undergo a red shift in its vibrational frequency upon formation of a H-bond, the CH bond of the molecules studied here follows the opposite ...

Fundamental Properties of the CH···O Interaction: Is It a True Hydrogen Bond?

Die Wasserstoffbrucke ist die wichtigste der gerichteten intermolekularen Wechselwirkungen. Sie spielt fur die molekulare Konformation, Aggregation und Funktion einer grosen Anzahl chemischer Systeme, die vom anorganischen bis zum biologischen Sektor reichen, wichtige Rollen. Die Forschung uber Wasserstoffbrucken stagnierte in den 1980er Jahren, wurde um 1990 aber wieder belebt und ist seither in schneller Bewegung. Die Wasserstoffbrucke wird heute als ein sehr breites Phanomen mit offenen Grenzen zu anderen Effekten begriffen. In den kondensierten Phasen gibt es dutzende Arten von haufig vorkommenden X−H⋅⋅⋅A-Wasserstoffbrucken und zusatzlich sehr viele weniger haufige Typen. Die Dissoziationsenergien uberstreichen mehr als zwei Grosenordnungen (etwa 0.2 bis 40 kcal mol−1). Innerhalb dieses Bereiches ist die Natur der Wechselwirkung nicht konstant, sondern ihre elektrostatischen, kovalenten und dispersiven Anteile variieren in ihren relativen Beitragen. Die Wasserstoffbrucke hat breite Ubergangsbereiche zur kovalenten Bindung, zur Van-der-Waals-Wechselwirkung, zur ionischen Wechselwirkung und zur Kation-π-Wechselwirkung. Wasserstoffbrucken konnen als beginnende Protonentransferreaktion aufgefasst werden, und fur starke Wasserstoffbrucken kann diese Reaktion bereits in einem fortgeschrittenen Stadium sein. In diesem Aufsatz wird versucht, einen zusammenhangenden Uberblick uber alle diese Aspekte zu geben.

Die Wasserstoffbrücke im Festkörper

The basis set extension (BSE) effects such as primary and secondary basis set superposition errors (BSSE) are discussed on the formal and numerical ground. The symmetry‐adapted perturbation theory of intermolecular forces offers an independent reference point to determine efficacy of some computational approaches aiming at elimination of BSSE. The formal and numerical results support the credibility of the function counterpoise method which dictates that the dimer energy calculated within a supermolecular approach decomposes into monomer energies reproduced with the dimer centered basis set and the interaction energy term which also takes advantage of the full dimer basis. Another consistent approach was found to be Cullen’s ‘‘strictly monomer molecular orbital’’ SCF method [J. M. Cullen, Int. J. Quantum Chem. Symp. 25, 193 (1991)] in which all BSE effects are a priori eliminated. This approach misses, however, the charge transfer component of the interaction energy. The SCF and MP2 results obtained withi...

Critical evaluation of some computational approaches to the problem of basis set superposition error

The second‐order induction energy in the symmetry‐adapted perturbation theory is expressed in terms of electron densities and polarization propagators at zero frequency of the isolated monomers This expression is used to derive many‐body perturbation series with respect to the Mo/ller–Plesset type correlation potentials of the monomers Two expansions are introduced—one based on the standard Mo/ller–Plesset expansion of electron densities and polarization propagators, and the second accounting for the so‐called response or orbital relaxation effects, ie, for the perturbation induced modification of the monomer’s Fock operators Explicit orbital formulas for the leading perturbation corrections that correctly account for the response effects are derived through the second order in the correlation potential Numerical results are presented for several representative van der Waals complexes—a rare gas atom and an ion Ar–Na+, Ar–Cl−, and He–F−; a polar molecule and an ion H2O–Na+ and H2O–Cl−; two polar molecules (H2O)2; and a rare gas atom and a polar molecule Ar–HCl and He–HCl It is shown that in the above systems, the significance of the correlation part of the induction energy varies from a very important one in the complexes of rare gas atoms and ions to a practically negligible one in the complexes of rare gases with polar molecules

Many‐body theory of intermolecular induction interactions

The potential energy surface of CH4‐H2O is calculated through the fourth‐order Mo/ller–Plesset perturbation theory. In an attempt to obtain basis‐set saturated values of interaction energies the extended basis sets are augmented by bond functions which simulate the effects of high‐symmetry polarization functions. The absolute minimum occurs for the configuration involving the C–H‐O hydrogen‐bond in which O‐H points toward one of the faces of the CH4 tetrahedron. The equilibrium C–O separation is equal to 6.8 a0 which corresponds to the bond energy of 0.83 kcal/mol. Due to basis set unsaturation of the dispersion energy the bond energy may still be underestimated by about 0.05 kcal/mol. The secondary minimum involving the C‐H–O hydrogen‐bond is some 0.2 kcal/mol less stable, and the corresponding C–O distance is longer by 0.6 a0. The anisotropy of the potential energy surface is analyzed via the perturbation theory of intermolecular forces. The binding in CH4‐H2O is chiefly due to the dispersion energy whi...

Ab initio study of the potential energy surface of CH4‐H2O

Nonadditive, multibody effects arising in the supermolecular Mo/ller–Plesset perturbation theory (MPPT) (IMPPT) calculations are classified and interpreted in terms of the exchange, induction, deformation, and dispersion contributions, as defined by the perturbation theory of intermolecular forces. As an example the many‐body effects in the equilateral Ar trimer and tetrahedral Ar tetramer, calculated through the MP4 level of theory with extended basis [7s4p2d], are reported and discussed. It is stressed that the ‘‘Heitler–London‐exchange plus dispersion’’ model for nonadditive effects is too attractive mainly because of the neglect of the second‐order exchange contribution.

Calculations of nonadditive effects by means of supermolecular Mo/ller–Plesset perturbation theory approach: Ar3 and Ar4

The potential energy surfaces for Ar–CO and He–CO were calculated at the fourth order Mo/ller–Plesset perturbation theory and analyzed using perturbation theory of intermolecular forces. Both the complexes reveal only one minimum related to the approximately T‐shaped geometry. For Ar–CO, our best ab initio estimates of Re and De are 3.70 A and 496 μhartrees, respectively, and the optimal angle Rg–com–O is about 80°. For He–CO, our best Re and De are 3.4 A and 100 μhartrees, respectively, at the optimal angle Rg–com–O of 70°. Our geometrical parameters agree very well with the experimental data. Our ab initio well depths are estimated to be within ±5% in error and are expected to be the most accurate in the literature so far. The De values were obtained with extended basis sets which included bond functions. Basis set effects on the dispersion and electrostatic correlation terms that are caused by bond functions were also analyzed. Both complexes are bound by dispersion forces, but the anisotropy of the in...

asiński

Papers

Critical evaluation of some computational approaches to the problem of basis set superposition error

Many‐body theory of intermolecular induction interactions

Ab initio study of the potential energy surface of CH4‐H2O

Calculations of nonadditive effects by means of supermolecular Mo/ller–Plesset perturbation theory approach: Ar3 and Ar4

Structure and energetics of van der Waals complexes of carbon monoxide with rare gases. He–CO and Ar–CO