10.4.5 Defining a New Type of Specific Contact; The Define Specific Contacts Dialogue Box

Hit the Contacts... button (located near to the bottom-centre of the main Mercury window), or select the top-level Calculate option followed by Contacts.... in the resulting pull-down menu, to bring up the Contacts dialogue box. Then hit Add in the Contacts dialogue box and pick Specific... to bring up the Define Specific Contacts dialogue box.

Alternatively, you can get straight to the Define Specific Contacts dialogue by right-clicking anywhere in the white list box under the main Mercury display area and selecting Add Specific... from the resulting menu.

Use the pull-down menus next to the entry boxes labelled Contacts between to specify the atom types of the contacting atoms.

Set the required upper and lower distance limits (see Section 10.4.1). These may be specified as absolute distances in Angstroms, or as distances relative to the sum of vdW radii of the atoms involved in the contact.

Specify whether the contacts are to be intermolecular only, intramolecular only, or whether both are allowed.

If intramolecular bonds are allowed, specify the minimum number of covalent bonds between the contact atoms (see Section 10.4.2).

The following settings will find intermolecular and intramolecular contacts between chlorine and oxygen atoms, subject to the constraints that (a) the contact must be at least 0.1Å shorter than the sum of vdW radii, and (b) if the contact is intramolecular, the atoms must be separated by at least 5 covalent bonds:

Hit Default followed by Apply if you want to return all the settings to their default values.