Perturbation theory hydrogen bonds

Milet A, Moszynski R, Wormer P E S and van der Avoird A 1999 Hydrogen bonding in water olusters pair and many-body interaotions from symmetry-adapted perturbation theory J. Phys. Chem. A 103 6811-19... 

Hitherto it has been assumed that Tg corresponds to the classical equilibrium (or quantum-mechanical average) distance between the non-bonded atoms in the absence of interaction. It is inherent in the proper application of first-order perturbation theory that the perturbation is assumed to be small. In the case of the hindered biphenyls, however, it is known from the calculations cited in the introduction that the transition state is distorted to a considerable extent. The hydrogen atom does not occupy the same position relative to the bromine atom that it... 

As for Erep, Ect is derived from an early simplified perturbation theory due to Murrel [46], Its formulation [47,48] also takes into account the Lrj lone pairs of the electron donor molecule (denoted molecule A). Indeed, they are the most exposed in this case of interaction (see Section 6.2.3) and have, with the n orbital, the lowest ionization potentials. The acceptor molecule is represented by bond involving an hydrogen (denoted BH) mimicking the set, denoted < > bh, of virtual bond orbitals involved in the interaction. 

The linear response theory [50,51] provides us with an adequate framework in order to study the dynamics of the hydrogen bond because it allows us to account for relaxational mechanisms. If one assumes that the time-dependent electrical field is weak, such that its interaction with the stretching vibration X-H Y may be treated perturbatively to first order, linearly with respect to the electrical field, then the IR spectral density may be obtained by the Fourier transform of the autocorrelation function G(t) of the dipole moment operator of the X-H bond ... 

In earlier theoretical studies Shen and coworkers used Hartree-Fock self-consistent-field (HF) calculations with different basis sets to study water complexes of anionic ONO—O-30. Two stable ONO—O isomers, cis and trans, formed hydrogen bonds with H2O molecules at different positions. Second-order Mpller-Plesset perturbation theory (MP2) with a 6-311+G(d,p) basis set has also been applied to the study of ONO—O-, (H2O), (n = 1 or 2) complexes31. Koppenol and Klasinc studied the cis and trans conformers as well as the transition state for torsional motion of ONO—O- at the HF/6-31(d) level32. In their calculations, the trans conformer is slightly more stable than the cis form, and the rotational barrier was thought to be quite high. However, correlated methods (MP2) were also used to study this molecule, and they predict that the cis conformer is more stable than the trans conformer33,34. 

The most extensive analysis of the nature of intermolecular interaction components in hydrogen-bonded complexes of nucleic acid bases is that performed by Toczylowski et al. [26], The authors presented the results of calculations obtained on the basis of the intermolecular Mpller-Plesset perturbation theory using... 

The complete description of hydrogen bond and van der Waals interactions requires of course the inclusion of electron correlation effects however, almost always, a very useful starting point for subsequent refinements is represented by a Hartree-Fock description, which serves as the basis for both perturbation theory and variational configuration interaction approaches to the treatment of electron correlation. 

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