Placement barycentric

Consider a barycentric placement of the skeleton of a molecule in space, for example the regular hexagon that is the skeleton of benzene. (There is no exact definition of skeleton , descriptions of it may read as follows The skeletal structure of an organic compound is the string of connected atoms that form the essential structure of the compound. The skeleton can consist of chains, branches and/or rings. ) Here is the skeleton of benzene (with axes) ... 

We use the following simplified version of the skeleton, assuming a barycentric placement in space, emphasizing the substitutable positions by bullets and introducing cartesian coordinates ... 

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