Dear Murpholino,
I must apologize, there was a mistake in may last email. The critical
parameter is, as you correctly pointed out, DSCA not RIPW and it is
necessary to try a range of values for DSCA. For this reason I am CCing
this to CCP4bb.
As you will be discovering, RIP phasing is not easy. We treat it like
SIR, but it is complicated by the presence of both positive and negative
difference peaks caused by radiation damage. Also density modification
is less effective for SIR and RIP than for SAD phasing. In the case of
SAD, just replacing negative density with zero improves the phases, but
this is not true of SIR and RIP, However using the anomalous signal as
well (RIPAS) helps, similar to SIRAS.
Best wishes, George
--
Prof. George M. Sheldrick FRS
Dept. Structural Chemistry,
University of Goettingen,
Tammannstr. 4,
D37077 Goettingen, Germany
Tel. +49-551-39-33021 or -33068
Fax. +49-551-39-22582
