[Pw_forum] Question on SCF

[Paolo Giannozzi]

If after the first 10, max 20 steps or so, the value of the 
"estimated scf accuracy" does not show any sign of decreasing, 
something nasty is happening. There is no point in insisting 
with more iteractions: either input data is wrong, or the system 
cannot find a sensible ground state for the structure it has,
with the constraints you are (implicitly) imposing. Since I do 
not see anything obviously wrong in your data, the second case 
is likely the correct one. Your system, containing magnetic
atoms, highly correlated electrons, an oxygen vacancy, seems
to me a good candidate as multiple source of trouble

> I just want to speed it up

make tests at Gamma point (K_POINT gamma), reduce the number of 
bands to the strict minimum (200 should be fine)

P.
-- 
 Paolo Giannozzi, Dept. Chemistry&Physics&Environment, 
 Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
 Phone +39-0432-558216, fax +39-0432-558222