[Wien] Deeper DFT question

[Laurence Marks]

I am posting this email in the hope that someone can give me a hint
about a "well-known" empirical DFT result, but one which I cannot
rationalize/justify. Maybe someone can provide a counter example,
which would prove that the result is not general.

The empirical result can be phrased by looking at two cases:
a) An scf run with the atomic positions at the equilibrium (i.e.
lowest energy) positions
b) An scf run with the atomic positions displaced from equilibrium,
perhaps rather a lot.

The empirical result is that a) converges faster, perhaps much faster
than b) -- assuming of course equally good/bad starting points for the
electron density (e.g. atomic densities).

N.B., this result, if correct, implies something about the
convexity/radius of convergence of the scf problem, and relates to the
performance of MSR1a.

-- 
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/
Research is to see what everybody else has seen, and to think what
nobody else has thought
Albert Szent-Gyorgi