Errors with rigid body refinements

helenmc

Hello,

I'd like to be able to get esd's on atomic coordinates for a refinement I've done which is constrained by two rigid bodies. When I use the do_errors command, I only get this for the bodies themselves not the atomic coordinates. Is there anyway of outputting esd's for each of the atoms through TOPAS, or do I just need to work that though myself?

Thanks,
Helen

mfisch

I think that is only possible since version 5 where this is done automatically.

Cheers
Martin

alancoelho

From the NEW5.PDF file found at http://www.topas-academic.net/

"2.5.1 Rigid body parameter errors propagated to fractional coordinates
Errors for fractional coordinates for sites defined as part of a rigid body are now propagated to the site fractional coordinates. The example rigid-errors\Aniline_I_100K_x.inp (by Simon Parsons) demonstrates equivalent refinements for the case of 1) using a rigid body and for the case 2) hand coding the fractional coordinates in terms of rigid body parameters but not in fact using a rigid body. Errors and convergence behavior in both cases are identical. In particular case (2), which has many computer algebra equations, takes approximately the same time per iteration as case (1); this demonstrates that the computer algebra does not noticeably affect computational speed even in cases where its use is plentiful."

alan