[Pw_forum] FW: cell optimization results seems to be a little strange

[Holger Hesske]

  Dear vega,

  next to the suggestion of Lorenzo to use the bfgs algorithm, the point in 
your input is the missing timestep for the cell dynamics with the 
Wentzcovitch algorithm. (see quantum-wiki) It looks like you got a 
non-evolving (or almost non-evolving) dynamics.
A second, more general remark on you input: Set up only the variables you 
really need (as Axel pointet out in several mails before: every non-written 
line is per definition a correct one).
It doesn't make any sense to set numbers with more than 14 digits (the code 
does not handle this) and in most cases 8 digits is more than enough, 
Think about, why you set etot_conv_thr so tight (don't mix it up with 
conv_thr, which seemed to be sloppy for this calculation ), while you set 
forc_conv_thr to be really sloppy? (Btw, is there any reason to set the 
cutoffs/thresholds to such precision?)

Hope this helps,

Holger 


-- 
Dr. Holger Hesske
Inst.f.Chemie-/Bioingenieurwissenschaft.
Wolfgang-Pauli-Str. 10
ETH Hönggerberg, HCI E 133
CH-8093 Zürich
Tel: +41 44 633 66 19
Fax: +41 44 632 11 63
E-Mail: holger.hesske at chem.ethz.ch