Intramolecular interactions theory

This simple relation rests on literal validity of both the intermolecular and the intramolecular interaction theories hence its unqualified acceptance is open to question). 

It should be noted that there is a considerable difference between rotational structure narrowing caused by pressure and that caused by motional averaging of an adiabatically broadened spectrum [158, 159]. In the limiting case of fast motion, both of them are described by perturbation theory, thus, both widths in Eq. (3.16) and Eq (3.17) are expressed as a product of the frequency dispersion and the correlation time. However, the dispersion of the rotational structure (3.7) defined by intramolecular interaction is independent of the medium density, while the dispersion of the vibrational frequency shift (5 12) in (3.21) is linear in gas density. In principle, correlation times of the frequency modulation are also different. In the first case, it is the free rotation time te that is reduced as the medium density increases, and in the second case, it is the time of collision tc p/ v) that remains unchanged. As the density increases, the rotational contribution to the width decreases due to the reduction of t , while the vibrational contribution increases due to the dispersion growth. In nitrogen, they are of comparable magnitude after the initial (static) spectrum has become ten times narrower. At 77 K the rotational relaxation contribution is no less than 20% of the observed Q-branch width. If the rest of the contribution is entirely determined by... 

This implies that the Jtx increments are independent of the molecule to which the constituent X belongs [190], and that tth = 0 (which is actually a serious flaw of this theory, since it has been measured that logP = 0.45 [191]). A very large number of ttx values are collected in a data bank [192,193], but numerous correction factors are necessary to account for structural features such as multiple bonds, branching, ring-joining and for intramolecular interactions [194]. These shortcomings prompted Rekker [195-199] and... 

In order to ensure accurate CG potentials, one needs to conduct MD simulations with a reliable atomistic potential model. The most desirable theoretical approach for the atomistic-scale simulations would be to use a level of quantum mechanics (QM) that can treat both intermolecular and intramolecular interactions with acceptable accuracy. Realistically, the minimal QM levels of theory that can adequately treat all different types of chemical forces are second order perturbation theory [32] (MP2)... 

This chapter is concerned with reaction rates, equilibria, and mechanisms of cyclisation reactions of chain molecules. A detailed analysis of the historical development of experimental approaches and theories concerning the intramolecular interactions of chain molecules and the processes of ring closure is outside the scope of this chapter. It must be borne in mind, however, that the present state of the art in the field is the result of investigations which have been approached with a variety of lines of thought, methods, and objectives. 

Equation (5.15b) is the fundamental assumption underlying London s theory, which is essential both for numerical evaluation and for physical interpretation of the perturbative expressions. Whereas short-range intramolecular interactions in (5.16a) and (5.16b) must be described with properly antisymmetric eigenfunctions satisfying... 

Kawabata44 has panted out on the basis of a simple network model that of the two derivatives, bW/blt and bW/bI2, the former should be related primarily to intramolecular forces such as the entropy force which plays a major role in the kinetic theory of rubber elasticity, while the latter should be a manifestation of intramolecular interactions. He predicted the possibility that bW/bI2 assumes negative values in the region of small defamation. In fact, the prediction was confirmed experimentally by Becker and also by the present authos. 

Answer. Three aspects of the scheme shown in Figure 13.2 may be examined by orbital interaction theory (a) the binding of CO compared to ethylene (b) the reactivity of coordinated carbonyl compared to ethylene with respect to reactivity toward intramolecular nucleophilic attack and (c) the migratory aptitude of alkyl versus carbonyl groups. 

The most advanced theories of relaxation phenomena in a system of entangled macromolecules is based on the dynamics of a single macromolecule. Dynamics of the tagged macromolecule is simplified by the assumption that the neighbouring macromolecules can be described as a uniform structureless medium and all important interactions can be reduced to intramolecular interactions. The dynamic equation for a macromolecule can be written as a modification of equation (2.1) for dynamics of macromolecule in viscous liquid... 

M. G. Veselov, Current Problems in Quantum Chemistry Quantum Chemistry Methods in the Theory of Intramolecular Interactions and Solids. Collection of scientific proceedings, Nauka, Leningradskoe Otd., Leningrad, 1987. 

Intramolecular interactions were introduced for the first time by van der Waals in 1873 he thus attempted to explain the deviation of the real gas from the ideal gas. In order to apply the ideal gas law equation to the behavior of real gases, allowance should be made for the attractive and repulsive forces occurring between molecules. From that time on, the dipole moment theory of Debye (1912) and the dispersion energy or induced dipole theory by London (1930) were the main driving forces of the research about intermolecular interactions. 

Density functional theory (DFT) calculations of two types of push-pull chromophores built around thiophene-based 7t-conjugating spacers rigidified by either covalent bonds or noncovalent intramolecular interactions (Figure 6) have been carried out to assign the relevant electronic and vibrational features and to derive useful information about the molecular structure of these NLO-phores <2003CEJ3670>. 

---