Theoretical study energy

Prasad, S. B., Biomass-fired steam power cogeneration system - A theoretical-study. Energy Conversion Manage 1995, 36 (1), 65-77. 

In the experimental and theoretical study of energy transfer processes which involve some of the above mechanisms, one should distingiush processes in atoms and small molecules and in large polyatomic molecules. For small molecules a frill theoretical quantum treatment is possible and even computer program packages are available [, and ], with full state to state characterization. A good example are rotational energy transfer theory and experiments on Fie + CO [M] ... 

The full quantum mechanical study of nuclear dynamics in molecules has received considerable attention in recent years. An important example of such developments is the work carried out on the prototypical systems H3 [1-5] and its isotopic variant HD2 [5-8], Li3 [9-12], Na3 [13,14], and HO2 [15-18], In particular, for the alkali metal trimers, the possibility of a conical intersection between the two lowest doublet potential energy surfaces introduces a complication that makes their theoretical study fairly challenging. Thus, alkali metal trimers have recently emerged as ideal systems to study molecular vibronic dynamics, especially the so-called geometric phase (GP) effect [13,19,20] (often referred to as the molecular Aharonov-Bohm effect [19] or Berry s phase effect [21]) for further discussion on this topic see [22-25], and references cited therein. The same features also turn out to be present in the case of HO2, and their exact treatment assumes even further complexity [18],... 

Although the same theoretical studies indicate very small energy differences between the syn and anti conformers of the 3-carbaldehydes of furan, thiophene and pyrrole with a slight preference for the syn conformer, in chloroform solution the furan- and thiophene-3-carbaldehydes adopt the anti conformers to the extent of 100 and 80% respectively (82X3245). However, A-substituted 3-(trifluoroacetyl)pyrroles exist in solution as mixtures of rotational isomers (80JCR(S)42). 

Natural convection occurs when a solid surface is in contact with a fluid of different temperature from the surface. Density differences provide the body force required to move the flmd. Theoretical analyses of natural convection require the simultaneous solution of the coupled equations of motion and energy. Details of theoretical studies are available in several general references (Brown and Marco, Introduction to Heat Transfer, 3d ed., McGraw-HiU, New York, 1958 and Jakob, Heat Transfer, Wiley, New York, vol. 1, 1949 vol. 2, 1957) but have generally been applied successfully to the simple case of a vertical plate. Solution of the motion and energy equations gives temperature and velocity fields from which heat-transfer coefficients may be derived. The general type of equation obtained is the so-called Nusselt equation hL I L p gp At cjl... 

Laminar Flow Normally, laminar flow occurs in closed ducts when Nrc < 2100 (based on equivalent diameter = 4 X free area -i-perimeter). Laminar-flow heat transfer has been subjected to extensive theoretical study. The energy equation has been solved for a variety of boundaiy conditions and geometrical configurations. However, true laminar-flow heat transfer veiy rarely occurs. Natural-convecdion effects are almost always present, so that the assumption that molecular conduction alone occurs is not vahd. Therefore, empirically derived equations are most rehable. 

Computer simulation techniques offer the ability to study the potential energy surfaces of chemical reactions to a high degree of quantitative accuracy [4]. Theoretical studies of chemical reactions in the gas phase are a major field and can provide detailed insights into a variety of processes of fundamental interest in atmospheric and combustion chemistry. In the past decade theoretical methods were extended to the study of reaction processes in mesoscopic systems such as enzymatic reactions in solution, albeit to a more approximate level than the most accurate gas-phase studies. 

Theoretical studies indicate that for dt < 2 nm the effect of strain energy exceeds that of the room temperature thermal energy, so that it is only at small nanotube diameters that the strain energy associated with nanotube... 

A theoretical ab initio study of the gas-phase basicities of methyldiazoles (90JA1303) included a discussion of the 4(5)-methylimidazole tautomer-ism. The RHF/4-31G calculations led to the conclusion that the 4-methyl tautomeric form 14a (R = Me, R = R = H) is 5.2 kJ moP more stable than its 5-methyl counterpart 14b. It was emphasized that this result is to be considered as basic-set dependent. However, a recent theoretical study [94JST(T)45] showed that, starting from the RHF/6-31G level, all the more accurate approximations indicate a higher intrinsic stability for the 4-methyl tautomer. At the MP2/6-31G level, the total energy of the 4-methyl tautomer is 0.7 kJ mol lower than that of the 5-methyl tautomer. Inclusion of solvation effects can, thus, strongly affect the position of the tautomeric equilibrium 14a 14b. Recently, a systematic theoretical study... 

A theoretical study based on PM3 frontier molecular orbital (FMO) and potential energy surface (PES) analysis at the RHF/6-31-I-G level was performed to examine the reaction of l-amino-2-ethoxycarbonylpyridinium mesitylenesulfonate and acrylonitrile in the presence of Hiinig s base leading to the formation of 3-cyano-4-hydroxy-l,2-dihydropyrido[l,2-ft]pyridazi-nium inner salt (54) (99JOC9001). The calculations indicated that both the... 

Ton-molecule reactions are of great interest and importance in all areas of kinetics where ions are involved in the chemistry of the system. Astrophysics, aeronomy, plasmas, and radiation chemistry are examples of such systems in which ion chemistry plays a dominant role. Mass spectrometry provides the technique of choice for studying ion-neutral reactions, and the phenomena of ion-molecule reactions are of great intrinsic interest to mass spectrometry. However, equal emphasis is deservedly placed on measuring reaction rates for application to other systems. Furthermore, the energy dependence of ion-molecule reaction rates is of fundamental importance in assessing the validity of current theories of ion-molecule reaction rates. Both the practical problem of deducing rate parameters valid for other systems and the desire to provide input to theoretical studies of ion-molecule reactions have served as stimuli for the present work. 

The synthesis and characterization of the monomeric amidinato-indium(I) and thallium(I) complexes [Bu C(NAr)2]M[But(NAr(NHAr)] (M = In, Tl Ar = 2,6-Pr2CgH3) have been reported. Both compounds were isolated as pale yellow crystals in 72-74% yield. These complexes, in which the metal center is chelated by the amidinate ligand in an N, j -arene-fashion (Scheme 33), can be considered as isomers of four-membered Group 13 metal(I) carbene analogs. Theoretical studies have compared the relative energies of both isomeric forms of a model compound, In[HC(NPh)2]. ... 

Recent theoretical studies have demonstrated that it is possible to calculate accurately adsorbate stmcture and energy levels, to explain trends with variations in metal composition, and to interpret and predict the influence of promoters and poisons on the adsorption of reactants. Additional efforts along these lines will contribute greatly to understanding how catalyst stmcture and composition influence catalyst-adsorbate interactions and the reactions of adsorbed species on a catalyst surface. With sufficient development of theoretical methods, it should be possible to predict the desired catalyst composition and stmcture to catalyze specific reactions prior to formulation and testing of new catalysts. 

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