[Pw_forum] SCF convergence - proposal

[Paolo Giannozzi]

[sorry for the previous truncated message, trying again...]

On Friday 20 February 2004 18:20, Konstantin Kudin wrote:

> Right now the code uses fixed mixing (0.7), which is
> sort of similar to doing V(rho_) with c1 and c2 always
> fixed

it's not that simple. Early versions of PWscf used Anderson mixing:
D.G. Anderson, J. Assoc. Comput. Mach. 12, 547 (1965). Later, we 
moved to a modified Broyden method: D.D. Johnson, Phys. Rev. B 
38, 12807 (1988).  Recently we have started to use mixing of charge
density instead of potential, a better criterion for the error to be
minimized, and an estimate for the dielectric response for highly
inhomogeneous cases. The present algorithm is quite sophisticated.
It may require some tuning, however, and how to tune it is not always
obvious. 

Anyway: your suggestion is most welcome. An algorithm that
converges no matter what would be highly desirable.

Paolo

-- 
Paolo Giannozzi             e-mail:  giannozz at nest.sns.it
Scuola Normale Superiore    Phone:   +39/050-509876, Fax:-563513 
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