Software GAUSSIAN

The authors are indebted to the Center for Computational Research (CCR) of the University at Buffalo for the use of its facilities and to Dr. J. L. Tilson (CCR) for his help concerning the Gaussian software. We are also indebted to Mr. Amadeu Sum and Prof. S. I. Sandler (University of Delaware) for useful discussions regarding the ab initio calculations. 

A series of molecular mechanics and ab initio calculations of an isolated single molecule have been performed with the Gaussian software package (using MM+ and STO-3G, 3-21G, 6-3IG and 6-3IG basis sets, respectively) to explore the expected positions of the peaks corresponding to intramolecular distances and also to determine the optimal procedure to find them. 

GAUSSIAN software (1998) Carnegie Office Park, Pittsburgh PA USA... 

The X-Pol method has been implemented in a developmental version of the Gaussian software package Although a single... 

Here, we will demonstrate the steps for modelling the Diels-Alder reaetion using the Gaussian software. 

There are methods that automate some of these steps. They are called composite methods because they combine results from several calculations to estimate the result that would be obtained from a more expensive calculation. The most popular families of composite methods are represented by Gaussian-3 (G3) theory [68,109] and CBS-APNO theory [110,111], where CBS stands for complete basis set. Both families of methods, which are considered reliable, include empirical parameters. The CBS theories incorporate an analytical basis set extrapolation based on perturbation theory, which is in contrast to the phenomenological extrapolation mentioned above. When the Gaussian software is used to perform these calculations, steps 2-, above, are performed automatically, with the result labeled G3 enthalpy (or the Hke) in the output file [20,99]. The user must still choose a reaction (step 1) and manipulate the molecular enthalpies (steps 5 and 6). The most precise composite methods are the Weizmann-n methods, which however are very intensive computationally [112]. 

Zhu et al. used Zr and Mg SSNMR experiments in 2008 to examine the local structure within two novel microporous zirconium silicate frameworks, AM-2 and AV-3 [54]. This study used magnetic fields of 9.4 and 21.1 T along with the QCPMG and DFS—QCPMG pulse sequences. In addition, ab initio calculations of Zr EFG tensor parameters were performed using the Gaussian software package [82],... 

Gaussian software, archiving chemical information, software development for the community, process control and process design software... 

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