To perform the conversion, the following input fields must be filled:
The format for the Atom contents field is
element1 sep element2 ... where sep can be a white space, a comma or a semicolon and
element1, elemnt2 ...are the chemical symbols of element 1, 2 ...
Interestingly, the Atom contents field can also be used to specify united atoms. The syntax is exactly the same but, in
that case, the element name must be replaced by the MMTK united atom code (e.g. CH3, CH2, CH, NH, NH2, NH3, OH, S ...).