Which programs require that the data be the 'standard' a.u.? None of
mine require this.
George
On 05/29/2012 03:44 PM, Ian Tickle wrote:
Mark, thanks for pointing that out, I see it now:
In P321 the only possible alternate indexing is (-h, -k, l): this is a
2-fold || c which is an operator of the hexagonal lattice but is not
an equivalent reflection.
The standard CCP4 a.u. is h = k, l>= 0 or h> k, k>= 0, so for
example (3,2,1) would be in the standard a.u. (3> 2 and 2>= 0). In
the alternate indexing this would be (-3, -2, 1); however it's
impossible to transform this to the a.u. with any non-inverting
equivalent. The only possibility is to invert the hand, i.e. to (3,
2, -1) which is again in the a.u..
So the required re-indexing operator to match (3, 2, -1) with (3, 2,
1) is (h, k, -l) which reindex won't allow without the LEFT keyword
(and you would be well-advised to avoid doing it with phase columns!).
Cheers
-- Ian
--
Prof. George M. Sheldrick FRS
Dept. Structural Chemistry,
University of Goettingen,
Tammannstr. 4,
D37077 Goettingen, Germany
Tel. +49-551-39-3021 or -3068
Fax. +49-551-39-22582
