Structure Editor comes complete with a function for checking chemical structures. Structure Checker searches for formal errors and unusual structural features. If a structure is formally incorrect, or Structure Checker considers there is some doubt about its validity, a Structure Check Results window appears with a list of errors and warnings. When this window is closed the program automatically selects the atoms and bonds, which are considered incorrect. As mentioned in the Program Limitation section, structures that are not connected are considered to be mixtures, which are reported as errors.

To check a structure:

• Click the Check Structure button  in the Structure Editor, or choose the Structure | Check Structure menu item.

Note: This option does not perform quantum mechanical or thermodynamical calculations concerning possible structure stability.

After finishing a structure drawing, you should always check it for errors before proceeding with any other procedure. Once the fragments and mechanisms generation is initiated, a structure is automatically checked for errors. If any error is discovered, the program prevents you from continuing with the generation.

Before running Generation of Fragments and Mechanisms and after finishing structure drawing in Fragmentation Library window structure check is automatically performed.