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[Hua Bao <hbao@purdue.edu>]

Dear Anglade Pierre-Matthieu,


Still, I cannot get a convergent wave function. First, I am a little 
confused about the word "tune"? I set iprcel 49, then get 4 converging 
steps, then set 44, get and 6 converging steps. I set 46 and get 4 
converging steps. If I set for 45 and get 2 converging steps. Am I able 
to set iprcel 4x and get exactly x converging steps?

I tried 49/44/46/45 for a sufficiently long time (100 steps), it just 
doesn't show any sign of convergence.  I did not try 14x yet because I  
am a little confused about the tune  procedure.

Thanks,
Hua

Anglade Pierre-Matthieu wrote:
> using kerker's preconditioner is not efficient in your case since you
> consider a cluster. So forget about diemac. Instead use
> iprcel 4x
> diecut 1
>
> The best is to tune the x in 4x so that it is the number of the last
> converging step. For instance
> if you try 49 and get
> ETOT1 -407 -407
> ETOT2 -408    -1
> ETOT3 -409    -1
> ETOT4 -408   +1
> ...
>
> You'd better try "iprcel 43".
> With this you should achieve perfect convergency in less than 50 steps.
> If this fails I recommand that you try "iprcel 14x". (with your
> previously determined x).
> You should get the required level of convergency in probably less than
> 20 steps eventhough they cost much more you'll win a lot of your time.
> Notice however that the computation associated with iprcel are not
> parallelized over band... sorry
>
> PMA
>
>
> On 8/29/07, Hua Bao <hbao@purdue.edu> wrote:
>   
> > Dear Anglade Pierre-Matthieu,
> >
> > Thank you for your fast reply. I am using infinite band, so I guess
> > parallel may help a little.
> > I am using MT type norm-conserving pseudopotential for both Ti and O
> > (22ti.pspnc and 8o.pspnc).
> >
> > Below is my input file and part of the output,
> > ionmov  3              # Use the modified Broyden algorithm
> > ntime   1000             # Maximum number of Broyden "timesteps"
> > tolmxf  1.0d-4         # Stopping criterion for the geometry
> > optimization : when
> > iscf    7
> > npulayit 20
> > chkprim 1
> > toldff  1.0d-4
> > xangst 9.186000    9.186000   11.779326
> > 10.506552   10.505191   12.167015
> > 7.865448    7.866809   12.167015
> > 9.186000    9.186000    8.877000
> > .........
> > #Definition of the unit cell
> > acell  15 15 15  angstrom
> > angdeg 90 90 90
> > ntypat 2
> > znucl 22 8
> > natom 33
> > typat 1 2 2 1 2 1 2 2 2 1 2 2 2 1 2 2 1 2 2 2 1 2 1 2 2 1 2 1 2 1 2 2 2
> > ecut 30.0         # Maximal kinetic energy cut-off, in Hartree
> > #Definition of the k-point grid
> > nkpt 1
> >
> > nstep 500          # Maximal number of SCF cycles
> > diemac 50
> >
> > Output,
> > .....
> >  Symmetries : space group P1 (#  1); Bravais aP (primitive triclinic)
> > ================================================================================
> >  Values of the parameters that define the memory need of the present run
> >    intxc =         0  ionmov =         3    iscf =         7     ixc
> > =         1
> >   lmnmax =         2   lnmax =         2   mband =        93  mffmem
> > =         1
> > P  mgfft =       144   mkmem =         1 mpssoang=         3     mpw
> > =     89463
> >   mqgrid =      3001   natom =        33    nfft =   2985984    nkpt
> > =         1
> >   nloalg =         4  nspden =         1 nspinor =         1  nsppol
> > =         1
> >     nsym =         1  n1xccc =      2501  ntypat =         2  occopt
> > =         1
> > ================================================================================
> > .....
> >  ETOT  1  -390.60418925724    -3.906E+02 1.162E-01 2.003E+05 6.522E-01
> > 6.522E-01
> >  ETOT  2  -399.15192426392    -8.548E+00 1.729E-01 9.015E+04 1.048E+00
> > 6.410E-01
> >  ETOT  3  -407.53310732403    -8.381E+00 4.573E-02 4.745E+04 7.852E-01
> > 4.791E-01
> >  ETOT  4  -407.92518738003    -3.921E-01 3.082E-02 3.906E+04 1.451E-01
> > 4.030E-01
> >  ETOT  5  -405.54214107012     2.383E+00 1.644E-02 7.648E+04 6.195E-01
> > 5.258E-01
> >  ETOT  6  -408.24685027392    -2.705E+00 1.358E-02 2.997E+04 6.768E-01
> > 3.641E-01
> > ......
> >  ETOT 50  -409.77792273642    -8.557E-03 2.940E-05 1.482E+03 4.318E-02
> > 9.077E-02
> >  ETOT 51  -409.78097373049    -3.051E-03 1.125E-05 2.254E+03 7.028E-02
> > 1.043E-01
> >  ETOT 52  -409.84803111241    -6.706E-02 2.862E-05 2.478E+02 5.466E-02
> > 6.845E-02
> >  ETOT 53  -409.79189318401     5.614E-02 1.107E-05 2.079E+03 6.247E-02
> > 9.658E-02
> >  ETOT 54  -409.82779081084    -3.590E-02 2.751E-05 6.042E+02 6.102E-02
> > 8.605E-02
> >  ETOT 55  -409.78546959552     4.232E-02 1.143E-05 1.367E+03 3.418E-02
> > 9.129E-02
> >  ETOT 56  -409.83178716613    -4.632E-02 2.502E-05 4.860E+02 7.159E-02
> > 9.624E-02
> > .........
> >  ETOT261  -409.86217751005     7.211E-04 4.555E-08 8.010E+01 6.128E-03
> > 7.429E-02
> >  ETOT262  -409.86060355976     1.574E-03 7.512E-08 1.062E+02 5.525E-03
> > 7.759E-02
> >  ETOT263  -409.86285205630    -2.248E-03 4.087E-08 6.501E+01 7.248E-03
> > 7.305E-02
> >  ETOT264  -409.85658369085     6.268E-03 6.611E-08 1.735E+02 1.226E-02
> > 7.614E-02
> >  ETOT265  -409.86055804058    -3.974E-03 3.425E-08 1.007E+02 5.539E-03
> > 7.763E-02
> >  ETOT266  -409.86273053407    -2.172E-03 6.215E-08 7.162E+01 1.099E-02
> > 7.444E-02
> >  ETOT267  -409.84672451979     1.601E-02 4.149E-08 2.413E+02 2.870E-02
> > 5.157E-02
> >  ETOT268  -409.85874398923    -1.202E-02 5.906E-08 1.028E+02 1.905E-02
> > 6.155E-02
> >  ETOT269  -409.85148059726     7.263E-03 3.656E-08 2.451E+02 2.618E-02
> > 7.902E-02
> > Anglade Pierre-Matthieu wrote:
> >     
> > > Hi,
> > >
> > > OK, it looks like your system is a difficult one. Please send the
> > > various input and relevant part of the output so that we can give you
> > > a better diagnose (just the change with respect to the first one you
> > > send will be sufficient). I'm quite astonished that you do not get
> > > perfect convergency following my previous advices. Is it possible that
> > > you did a mistake ? Or are you using PAW ?
> > >
> > > About parallel computing:
> > > - If you use a single k-point, you must rely on the band FFT. It
> > > requires a fast network. Forget about it if you use ethernet.
> > > -If you have a few k-point use as much processor as k-point .
> > > Parallelism will decrease the time per step. But never enhance the
> > > convergence you get.
> > >
> > > Regards
> > >
> > > PMA
> > > O
> > >       
> >     
>
>
>