On Thu, 2010-08-12 at 08:57 +0000, MARTYN SYMMONS wrote: > Zero occupancy is generally a deprecated way of dealing with missing > density as it is confusing for less experienced user of the > coordinates. I think zero occupancy can be useful during refinement as > the atoms help fill space (or for example satisfy NCS restraint > format requirement) but then these atoms can be stripped out before > deposition. They should in any case never be included in B-factor > refinement as they will skew the statistics and possibly the B-factor > restraint model. Zero occupancy may be a bad idea for yet another reason - the atoms will displace bulk solvent and produce what is essentially a hole in the structure. It may be justified if you are trying to fill the empty internal cavities, but for atoms missing from density it seems like a wrong approach. -- "I'd jump in myself, if I weren't so good at whistling." Julian, King of Lemurs