Molecular Shape Analysis
Molecular shape analysis (MSA) is a vital first step of many quantitative structure-activity relationships (QSAR) investigations. This example illustrates how to classify molecular shape using the principal moments of inertia (PMI) and how to visualize the shapes using a PMI plot.
Consider three molecules with different shapes.
Compute 3D coordinates for the molecules and find the principal moments of inertia.
The principal moments are normalized by dividing the two smaller moments by the largest moment.
Using the principal moment ratios as coordinates, these shapes form the corners of a triangle.
Compare the shape for a collection of molecules, using the principal moment ratios for coordinates and 3D plots for tooltips.