On Fri, 2010-12-10 at 22:40 +0000, Ian Tickle wrote:
> Application of a symmetry operator to
> a point on a special position which is unchanged by the operator
> doesn't generate a symmetry copy of the point, because there is no
> symmetry copy of such a point!
Why not? Symmetry-related copy may be considered just that - copy
produced by a symmetry operator. What advantage do you gain by
restricting it to only those that result in physically different point?
There is one excellent point that you made in some past exchanges - that
deposited structures are mathematical models and they do not always have
to make strict physical sense. This seems to be just such case - one
does not have three zincs in that spot with each being gone two thirds
of the time, but making the model physically meaningful would require
perhaps dropping to P1 and implementing NCS to enforce crystal symmetry.
So compromising on the physical meaning of the atom record seems like a
small price to pay. This feels odd - I seem to be arguing "your
side" :)
Cheers,
Ed.
--
"I'd jump in myself, if I weren't so good at whistling."
Julian, King of Lemurs
