[Wien] Slow force convergence in mixer

[Laurence Marks]

A "feature" of the current mixer is that sometimes, particularly for
large cells, force convergence can be slow. For instance, :DIS may be
as small as 1E-5 or 1E-6 before the forces converge to -fc 1 or even
-fc 2. Does anyone have any idea what the physics behind this is?
(Wild ideas, i.e. "maybe it is XYZ" welcome.)

N.B., if I could understand the physics, I can probably condition the
mixer to eliminate this and thereby improve it, but without an
understanding of why I cannot. I suspect the Hellman-Feynman forces,
but....

-- 
Laurence Marks
Department of Materials Science and Engineering
MSE Rm 2036 Cook Hall
2220 N Campus Drive
Northwestern University
Evanston, IL 60208, USA
Tel: (847) 491-3996 Fax: (847) 491-7820
email: L-marks at northwestern dot edu
Web: www.numis.northwestern.edu
Chair, Commission on Electron Crystallography of IUCR
www.numis.northwestern.edu/
Electron crystallography is the branch of science that uses electron
scattering and imaging to study the structure of matter.