double OEGetCovalentRadius(unsigned int elemno)
Returns the covalent radius of the element specified by the given atomic number. The covalent radius of an atom is typically used in bonding calculations, such as the function OEDetermineConnectivity. A value of zero is returned for elements other than those commonly found in organic molecules. The actual values are those prescribed by the Cambridge Crystallographic Database (http://www.ccdc.cam.ac.uk).