[cctbxbb] cctbx conventions

[Luc Bourhis]

Hi,

f’’ is positive (c.f. the tables in henke_xxx.cpp and sasaki_xxx.cpp in build/cctbx/eltbx) and f + f’ + i f’’ is used (c.f. cctbx/xray/structure_factors_simple.h: this is not used in production code but all the more optimised production code shall give the same result at that simple implementation).

Best wishes,

Luc Bourhis


> On 8 Oct 2018, at 16:32, Graeme.Winter at Diamond.ac.uk <Graeme.Winter at diamond.ac.uk> wrote:
> 
> HI Folks,
> 
> Question from a colleague - any ideas?
> 
> Many thanks Graeme
> 
> Begin forwarded message:
> 
> From: "Bombardi, Alessandro (DLSLtd,RAL,SCI)" <alessandro.bombardi at diamond.ac.uk<mailto:alessandro.bombardi at diamond.ac.uk>>
> Subject: cctbx conventions
> Date: 8 October 2018 at 14:54:10 BST
> To: "Winter, Graeme (DLSLtd,RAL,LSCI)" <Graeme.Winter at Diamond.ac.uk<mailto:Graeme.Winter at Diamond.ac.uk>>
> 
> Hi Graeme,
> 
> I am trying to understand the convention used by cctbx,
> for the anomalous part of the atomic scattering factor.
> Do you know if it is written as
> f+f'+if'' with f'' >0
> 
> or with
> 
> f+f'-if'' with f'' >0
> 
> can you help me?
> 
> All the best,
> Alessandro
> 
> 
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