Phase QSAR method included

Figure 13.11 Overview diagram of the NCTR Four-Phase approach for priority setting. In Phase I, chemicals with molecular weight < 94 or > 1000 or containing no ring structure will be rejected. In Phase II, three approaches (structural alerts, pharmacophores, and classification methods) that include a total of 11 models are used to make a qualitative activity prediction. In Phase III, a 3D QSAR/CoMFA model is used to make a more accurate quantitative activity prediction. In Phase IV, an expert system is expected to make a decision on priority setting based on a set of rules. Different phases are hierarchical different methods within each phase are complementary.

This section covers ab initio and density functional theory (DFT), semi-empirical and empirical, and molecular mechanics and molecular dynamics methods. For gas-phase structure determinations, a refinement to the use of ab initio calculations the SARACEN (Structure Analysis Restrained by Ab initio Calculations for Electron diffractioN) method, and other relevant theoretical and computational chemistry techniques, including quantitative structure-activity/property relationship (QSAR/QSPR) models for prediction of biological activity and physicochemical properties, are also covered. 

Ab initio crystal prediction provides a density value and important information about the positions of the atoms in the unit ceU, invaluable information that can be used to construct molecular models for use in other simulations or might be useful in analysis of experimental results of dynamic response (e.g., directional shock sensitivity). Unfortimately, the methods are computationally intensive and analysis of the results is not trivial For assessment of potential performance, often the user only needs the value of the crystal density at room conditions. For such calculations, QSAR/QPSR approaches are extremely attractive due to their ease of use and speed. Several QSPR-type approaches have been used to predict condensed phase densities of molecular organic systems [37-45] some of which are included in EM research. In some of the QSPR-type approaches, a property called molecular... 

Phases I and II are theoretical-computational and, when approached through statistical or multivariate methods, the OECD (Organization for Economic Cooperation and Development) principles for a QSAR study must include the following information (OECD, 2007 Putz et al., 2011a) ... 

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