# OEGetHBondAcceptorCount¶

unsigned int OEGetHBondAcceptorCount(const OEChem::OEMolBase &mol)


Returns the number of hydrogen-bond acceptors in a molecule based on the definition in the work of Mills and Dean ([MillsDean-1996]) and also in the book by Jeffrey ([Jeffrey-1997]). It is defined to be the number of atoms which match any of the following:

• degree 2, aromatic, non-positive nitrogens. An example is shown below.
• electron rich or negative, valence less than 4, non-aromatic nitrogens. An example is shown below.
• negatively charged or not electron withdrawn, neutral, non-aromatic oxygens. An example is shown below.
• degree 1, double bonded, electron rich, non-aromatic sulfur. An example is shown below.