Second-order group contribution method

A natural extension of the bond energy approach is to account for interactions close to the chemical bond in question (which certainly affect the stability, and hence the thermodynamic properties). Based on this concept, a number of group contribution methods have been developed over the years, and many of these methods have been reviewed in Ref. 171. Benson s second-order group contribution method, probably the most successful and widely embraced method, was developed some 30 years ago as an improvement to bond energy (or bond contribution) methods for the prediction of thermochemical properties.167 This improvement was accomplished by accounting for ... 

In summary, we would like to emphasize the two current capabilities of the CHETAH program. The first is the estimation of gas phase thermodynamic data over the range of 25-1200°C, using Benson s second order group contribution method. The second capability of CHETAH is a hazard appraisal. This uses thermodynamic data to... 

Pure, low temperature organic Hquid viscosities can be estimated by a group contribution method (7) and a method combining aspects of group contribution and coimectivity indexes theories (222). Caution is recommended in the use of these methods because the calculated absolute errors are as high as 100% for individual species in a 150-compound, 10-family test set (223). A new method based on a second-order fit of Benson-type groups with numerous steric correctors is suggested as an alternative. Lower errors are claimed for the same test set. 

A group contribution method, specifically, the second-order law, Is adopted In this work for estimating the physical and thermodynamic properties and functions of organic chemicals. 

Mattei, Kontogeorgis and Gani (2013) have recently shown that the CMC for a wide range of non-ionic surfactants can be predicted by a group contribution method using first, second and third-order groups. The agreement is very satisfactory, as... 

The enthalpy of formation can be determined theoretically and experimentally. The theoretical methods can be defined as those which use bond contributions and the ones which use group contributions. The bond contribution techniques can be characterized as zero, first, second, or higher order methods, where zero is elemental composition only, first adds the type of bonding, second adds the next bonded element, and higher adds the next type of bond. A survey of typical theoretical methods is shown in Table 2.6. 

Application of this method to the heat content of homologous series of organic compounds in the liquid state would result in a non-linear course of the heat content as a function of the number of methylene groups. This is exactly what is found experimentally for the heat of fusion as a function of the number of methylene groups. A second order additivity rule, however, is too complicated for practical application if a large number of structural groups is involved. It would require the compilation of innumerable group pair contributions. 

In addition to MP2, MP3, and MP4 calculations, CCSD(T), CASSCF, FOCI (First-Order Configuration Interaction), and sometimes SOCI (Second-Order Configuration Interaction) approaches have been used to ensure the convergence of the results. The complete definitions of the variational spaces used are given in [61,62,63]. Electronically-excited states have been obtained by means of the MC/P method, recently developed in our group [64,65] it couples a variational treatment to deal with the nondynamic correlation effects and a perturbation treatment to account for the dynamic correlation effects as well as the non-dynamic effects not treated at the variational level becanse of their limited contributions to the phenomena investigated. All electronic transitions reported here are vertical transition energies. 

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