From a study of WHAT IF's database of high quality structures it was
determined that no pair of non-hydrogen-bonded atoms
should have an inter-atomic distance more than 0.4 Ångstrom shorter than
the sum of the two Van der Waals radii. For hydrogen bonded atoms this
limit was found to be 0.55 Ångstrom.
In this server, all interatomic distances between non-bonded atoms are
calculated, and verified against these rules. If two atoms do come closer,
the amount by which the contact is too close is printed in a table. In the
table it will be indicated whether the bump is between symmetry relatives
(inter) or within the given asymmetric unit (intra).
A bump will never be reported between two atoms for which the sum of their
atomic occupancies is less than 1.0
If you have detected any error, or have any question or suggestion,
please send an Email to Gert Vriend.
Roland Krause, Maarten L Hekkelman, Jens E Nielsen,