[Rdkit-discuss] Fwd: Chem.Descriptors.ExactMolWt

[Curt F. <cur...@gm...>]

Hi RDKit users,

Should we expect the ExactMolWt() function from the Descriptors module to
know about the mass of electrons?  I initially expected that it would, and
thus was surprised by this behavior:


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> *proton_smiles = '[H+]'proton =
> Chem.MolFromSmiles(proton_smiles)proton_mass =
> Descriptors.ExactMolWt(proton)H_atom_smiles = '[H]'H_atom =
> Chem.MolFromSmiles(H_atom_smiles)H_atom_mass =
> Descriptors.ExactMolWt(H_atom)print proton_massprint H_atom_massprint
> rdmolops.GetFormalCharge(proton)print rdmolops.GetFormalCharge(H_atom)*



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> *1.0078250321.00782503210 *


That is, the proton and the neutral hydrogen atom have the same "exact"
mass.  But since electrons weigh 0.0005485799 Daltons, I was hoping that
*Descriptors.ExactMolWt(proton) *would return 1.00727645.

Am I misunderstanding what this function is for, or is this a bug?

Curt