MoleculeEquivalentQ

As of Version 13.0, MoleculeEquivalentQ has been superseded by MoleculeMatchQ.

MoleculeEquivalentQ[mol₁,mol₂]

gives True if mol₁ and mol₂ represent equivalent molecules and gives False otherwise.

Details

Two molecules are by default considered equivalent if there is a reordering of atom and bond lists that makes them the same, including any defined stereochemistry.
Atoms are considered equal if their atomic number, charge and mass number are the same. Bonds are considered equal if they have the same bond order.
For the purpose of equivalence testing, implicit and explicit hydrogen atoms are treated the same.
MoleculeEquivalentQ[mol₁,mol₂,…] gives True if all of the mol_i are equivalent.

Methane and the ammonium ion have identical connectivity but different atoms, so they are not equivalent:

Even though the underlying graphs are isomorphic, the molecules are not equivalent:

When molecules are the same, apart from the ordering of their atoms and bonds, MoleculeEquivalentQ will return True:

If the stereochemistry is different, then the molecules are not considered equivalent:

Test molecules with isotopic substitutions:

Implicit and explicit hydrogen atoms are treated the same by MoleculeEquivalentQ:

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