[Pw_forum] Fwd: Error during vc-relax process

[Paolo Giannozzi]

On Thu, Jun 4, 2015 at 1:45 PM, saswata halder <sanky.h at gmail.com> wrote:

"from checkallsym : error #         1
>      some of the original symmetry operations not satisfied ."
>

numerical noise may lead to the loss of the original symmetry. This usually
happens after many iterations.
If it happens after the first calculation, you have constraints that break
the symmetry.

    etot_conv_thr=1.0D-8
>

you do not need such a low threshold

>    forc_conv_thr=1.0D-6

as above

>    press_conv_thr=0.2D0

this is not here but in &cell

>    disk_io='high'

do not use this unless you have a good reason to

 >   ecutwfc = 80.0, ecutrho=800

you should not specify ecutrho for norm-conserving pseudopotentials

>  occupations='fixed',    smearing='gaussian', degauss=0.07

incompatible options: do you want fixed occupancies or smearing?

 >   diagonalization='cg',

don't use this unless you have a good reason to

>    conv_thr =  1.0D-9

usually you do not need such a low threshold

>    electron_maxstep=1000

way too many

> O  0.245 0.00  0.00  1 0 0
> O  0.755 0.00  0.00  1 0 0
> O  0.00  0.245 0.00  0 1 0
> O  0.00  0.755 0.00  0 1 0
> O  0.00  0.00  0.245 0 0 1
> O  0.00  0.00  0.755 0 0 1

if you fix positions (the "0" in the last three columns), you may break
symmetry

> It would be helpful if you can please explain what the error means and
> suggest how I can fix it so that I may carry out the phonon calculations.

don't even think performing a phonon calculation until you fully understand
self-consistent calculations

Paolo
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