[sharp-discuss] sharp error: No column "FP" of type "F" found in file

Clemens Vonrhein vonrhein at globalphasing.com
Fri Nov 4 14:32:15 CET 2011


Hi Mark,

On Fri, Nov 04, 2011 at 02:15:41PM +0100, Mark J van Raaij wrote:
> I have never done "MR-SAD" (i.e. MR plus peak) in Sharp so will leave that part for the experts - but it is easy to do in AutoRickshaw or Phenix.
> For MR-MAD (MAR plus two or more wavelengths) I don't know if there is software that can do that easily...

Those MR-XYZ methods that are popping up are basically what SHARP
was/is doing for 10+ years - we talk about 'external phase
information'. You have all your reflection data and a set of phases
(e.g. from MR) and SHARP will do all the scale refinement,
non-isomorphism refinement etc taking into account those additional
phases.

Nothing fundamentally magic about it: instead of having phases from HA
sites (of 1, 2 ... N datasets) you put the MR phases into the mix. Of
course, that mix has to be done properly! It then allows finding of HA
sites from the LLG residual maps based on those MR phases.

So SHARP is general and can do the PHI-XYZ method where PHI is a set
of phases (MR or whatever) and XYZ is your favourite abreviation (SAD,
MAD, SIR, SIRAS, MIR, MIRAS, MAD+native, ...).

A note to new users or users with tricky problems like that: it does
help a great deal to stop thinking in simple terms like SAD, MAD or
such. These are only (often useful) subsets of a much bigger picture -
SHARP refers to it as compound, crystal, wavelength and batch in its
extremely flexible hierarchy.

If we had limited SHARP to a single case (PHI=MR and XYZ=SAD) we might
have come up with a sexy name like MR-SAD as well ... it's always a
bit less 'brandable' and more difficult for marketing buzzwords if you
stay open and generic ;-)

Cheers

Clemens

PS: if anyone wants additional documentation about "combining X
derivatives with Y anomalous datasets, Z native datasets and some MR
models", please drop us a line and we will try to write up more on the
SHARP/autoSHARP wiki!


-- 

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