[phenixbb] gridding of maps & coot

Roger Martin roger at quantumbioinc.com
Wed Mar 18 06:49:28 PDT 2015

On 03/17/2015 08:15 PM, Paul Emsley wrote:
> On 17/03/15 18:22, Roger Martin wrote:
>> and if symmetry operations are added to the ccp4 binary file coot has 
>> issues with asu (asymmetric unit) fitting to the grid
> The nature of the issues that Coot has with ASU fitting to the grid is 
> not clear to me.
It is the combination of grid dimensions from the determine_gridding(in 
cctbx and not spacegroup aware) and the symmetry operators. I haven't 
looked at coot's code but the behavior indicates it wants to avoid 

if the grid dimension isn't fitting an integer number of ASU' in x or y 
or z.

The second determine_gridding(in cctbx and spacegroup aware) works. But 
phenix does not use it because it doesn't set the symmetry_flags in its 
initialization of 

> Is the problem here that Coot (and CCP4's) ASU is inconsistent with 
> that of cctbx (for a given spacegroup)?
> Paul.
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