The ABINIT Users Mailing List ( CLOSED )

[Patrick Welche <prlw1@newn.cam.ac.uk>]

On Wed, Nov 24, 2004 at 01:14:34PM +0900, Masayoshi Mikami wrote:
> On 2004/11/24, at 2:29, Patrick Welche wrote:
> >P.S.: I use getwfk -1 during the calculation, but then it seems I can't
> >make use of the last _WFK file, as apparently at most one of getwfk and
> >irdwfk can be non zero. Is there a way of not starting again from a 
> >random wavefunction?
> 
> In any case, for my cases so far, I often use
>  irdwfk 1
>  restartxf 1
> from the 2nd input.
> (here *o_WFK created in the 1st run  is renamed
>  as *i_WFK beforehand ...)

I understood the documentation to mean that irdwfk 1 would just read
the wavefunction initially, but start from that one for each Broyden
step, rather than start from the previous Broyden step's wavefunction,
which is why I used getwfk -1. I'll try with irdwfk 1 restartxf 1!
Thank you!

That seems to deal with the wavefunctions, but my problem was the atomic
positions - how can I restart from those? Do I tried cut and pasting
acell, rprim, xred, typat from the _DDB file into the input file and
got the errors below. getxred and friends look like good candidates, but
mention they are used for the ndtset>0 case, whereas here I have ntime>0..

Attached is the original working input file, which didn't quite manage to
converge after 30 steps, and from where I would like to restart..

Cheers,

Patrick

> >I suspect this is a FAQ, but I didn't see any references to the
> >problem I see..
> >
> >Essentially, I try an ionmov 3 optcell 2 calculation for a Cccm (spgroup 
> >66)
> >crystal. My original input file just has the natrd 12 attoms in it, with
> >a (1,0,0)(0,1,0)(0,0,1) rprim, setting brvltt -1 to find the real rprim.
> >I just enter xred for the 12 atoms and let the spgroup find all natom 58.
> >(116 in the conventional orthorhombic unit cell)
> >
> >Time passes and 30 Broyden steps later, I have not converged. So the
> >problem now is, how to restart where I stopped? (Maybe increasing ecut
> >from 25 to 35 at the same time)
> >
> >I cut and pasted the acell, rprim, xred, typat from the output file
> >back into the input file. As rprim now looks like a real primitive
> >unit cell, I thought I would take brvltt -1 out (and of course removed
> >natrd 12 as there are 58 atoms listed)
> >
> >This gave me the error:
> >
> > chkprimit : ERROR -
> >  According to the symmetry finder, the unit cell is
> >  NOT primitive. The multiplicity is  2 .
> >  The use of non-primitive unit cells is allowed
> >  only when the input variable chkprim is 0.
> >  Action : either change your unit cell (rprim or angdeg),
> >  or set chkprim to 0.
> >
> >yet the rprim is essentially
> >(sqrt(3)/2,1/2,0),(-sqrt(3)/2,1/2,0)(0,0,1)
> >which seems right. For the conventional cell, I would expect 
> >multiplicity 2 as it is C-centered, with 116 atoms.
> >
> >For no logical reason, I put brvltt -1 back in, and get:
> >
> > chkorthsy: ERROR -
> >  The symmetry operation number    3 does not preserve
> >  vector lengths and angles.
> >  The value of the residual is  6.1161E+04.
> >  Action : modify rprim, acell and/or symrel so that
> >   vector lengths and angles are preserved.
> >   Beware, the tolerance on symmetry operations is very small.
> >
> >So I am confused: the calculation used the symmetry and gave me an output
> >file. How come I need to modify the output? (Should I not have picked xred
> >but rather xcart or some other version of the coordinates?)
# Cordierite: First, find structure

# Optimization of the lattice parameters
optcell 2        # 3 from constant volume
ionmov  3
ntime  30
dilatmx 1.05
ecutsm  0.5

# Definition of the k-point grids
kptopt  1
nshiftk 1
shiftk 0.0 0.0 0.5
ngkpt 2 2 2
getwfk -1

# SCF parameters
#ndtset 8 ecut: 5 ecut+ 5 # for(ecut=5;(loop 8 times);ecut+=5)
# ecut 5-10 for Si 25-35 for O # keep rprim and acell constant
ecut 25.0
nstep 20
toldfe 1.0d-6
diemac 12 # that's OK for Si, the Al and Mg would want higher

# The unit cell
spgroup  66       # Cccm
brvltt -1
acell 3.6102226436E+01  2.0850114272E+01  1.9324560696E+01
rprim 1.0 0.0 0.0
      0.0 1.0 0.0
      0.0 0.0 1.0
# The atoms
natom  58
natrd  12
ntypat   4      # Mg, Al, Si, O
znucl   12 13 14 8
# Mg4 Al8 Si10 O36
typat 1 2 3 3 3 2 4 4 4 4 4 4
xred
0.336373    0.000000    0.250000
0.250000    0.250000    0.251999
0.000000    0.500000    0.250000
0.190665    0.075826    0.000000
0.131799    0.763047    0.000000
0.051368    0.305139    0.000000
0.245601    0.899020    0.355696
0.062992    0.584209    0.348153
0.829228    0.690631    0.355808
0.041289    0.754546    0.000000
0.123099    0.184775    0.000000
0.165713    0.917748    0.000000