Re: RANTAN

[J Yao <jy1@york.ac.uk>]

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Dear Dirk,

(1) |Fph-Fp| should be used to calculate E-values.
(2) RANTAN works with E values only.
(3) You should calculate E-map with WT1*E*exp(i*PHI1), then run PEAKMAX to
    find out heavy atom positions.

Cheers.

Jia-xing.

----------------------------------------------------------------------
Dr. Jia-xing Yao                            Tel. 44-(0)-1904-432565.
Department of Chemistry                     Fax. 44-(0)-1904-410519.
University of York                          Email. jy1@york.ac.uk
Heslington, York, YO10 5DD UK.
----------------------------------------------------------------------

On Wed, 28 Apr 1999, Kostrewa, Dirk {PRPC~Basel} wrote:

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> ***    CCP4 home page http://www.dl.ac.uk/CCP/CCP4/main.html    ***
> 
> Dear CCP4 users,
> 
> I would like to try RANTAN for the determination of heavy atom positions
> from a derivative data set. However, from the documentation (CCP4 v3.5.1) it
> is not quite clear to me how to do it. Here are my questions to those of you
> who have successfully applied RANTAN:
> 
> (1) which coefficients do you take as the source for calculating E-values:
> FPH or |FPH-FP| ?
> (2) does RANTAN also work with origin-removed (E**2-1) coefficients ?
> (3) how do you convert the results to heavy atom positions ? do you
> calculate an electron density map with Fourier coefficients
> WT1*E*exp(i*PHI1) or with coefficients WT1*|FPH-FP|*exp(i*PHI1) and run
> PEAKMAX then, or is done completely different ?
> 
> Any hints are welcome!
> 
> Kind regards,
> Dirk.
> 
> *******************************************************
> * Dirk Kostrewa                phone: +41-61-688-7750 *
> * F.Hoffmann-La Roche Ltd.       fax: +41-61-688-7408 *
> * PRPC-S B65/R312                                     *
> * CH-4070 Basel, Switzerland                          *
> * e-mail: dirk.kostrewa@roche.com                     *
> *******************************************************
> 
> 
>