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["Anglade Pierre-Matthieu" <anglade@gmail.com>]

1)using an homogeneous (=bulk) preconditionner is not recommended for you problem. You must prefer a better approximation of the dielectric respons function (iprcel=49).
2) You may prefer iscf 7 which is a bit safer. However for big system whatever iscf you choose you'll need more bands "nbands" (or this means that there is less than 1/20 electrons per atom in the valence of your system) and more steps "nstep".
3) You kpoint sampling thought very dense for such a big system doesn't looks like being optimized. Are you sure it is the best choice for the level of precision you want.
4) If you wan't your calculations to converge to something (even unreallistic) you must have a sufficient ecut. I don't know your pseudo and neve have done computations in nitrogene and boron but ecut=6 seems quite small.

regards

On 4/28/06, msmajdoub@uh.edu <msmajdoub@uh.edu> wrote:

Dear Abinit users,

I have run the piezoelectric calculation for Boron Nitrie Nanotube. However, the code crashes. The maximum number of steps is 40(nstep 40). Itearation reaches 40 and I am getting big values of residuals.Please have a look at a part of the output file that I got and at the input file I generated.
I am worrying if I had made a mistake in the input file (value of certain parameters) or should I increase the nstep value so I could get convergence.
If I should increase nstep how much it should be? Is there any errors or problems in the input file.
Your comments and help are welcomed.
Please help!

Thanks in advance.

Regards,






In the output file:

########################the 0utput file#####################################
chkinp: Checking input parameters for consistency, jdtset= 1.

chkinp: Checking input parameters for consistency, jdtset= 2.

chkinp: Checking input parameters for consistency, jdtset= 3.

================================================================================
== DATASET  1 ==================================================================

Real(R)+Recip(G) space primitive vectors, cartesian coordinates (Bohr,Bohr^-1):
R(1)=  6.5289350  3.7694824  0.0000000  G(1)=  0.0765822  0.1326442  0.0000000
R(2)= -6.5289350  3.7694824  0.0000000  G(2)= - 0.0765822  0.1326442  0.0000000
R(3)=  0.0000000  0.0000000 12.2777954  G(3)=  0.0000000  0.0000000  0.0814478
Unit cell volume ucvol=  6.0433042E+02 bohr^3
Angles (23,13,12)=  9.00000000E+01  9.00000000E+01   1.20000000E+02 degrees

getcut: wavevector=  0.0000  0.0000  0.0000  ngfft=  18  18  30
         ecut(hartree)=      6.000   => boxcut(ratio)=   2.16976

--- Pseudopotential description ------------------------------------------------
- pspini: atom type   1  psp file is ./bh2.fhi
- pspatm: opening atomic psp file    ./bh2.fhi
Boron, fhi98PP : Hamann-type, LDA, Perdew-Zunger-Ceperley-Alder (no spin-polarization) , l=2 local
   5.00000   3.00000      60327                znucl, zion, pspdat
    6    2    2    2       453   0.00000      pspcod,pspxc,lmax,lloc,mmax,r2well
  No XC core correction.
  1.024700          amesh (Hamman grid)
pspatm: epsatm=     2.94191637
         --- l  ekb(1:nproj) -->
             0    2.301173
             1   -0.722906
pspatm: atomic psp has been read  and splines computed

- pspini: atom type   2  psp file is ./nh2.fhi
- pspatm: opening atomic psp file    ./nh2.fhi
Nitrogen, fhi98PP : Hamann-type, LDA, Perdew-Zunger-Ceperley-Alder (no spin-polarization), l=2 local
   7.00000   5.00000     60327                znucl, zion, pspdat
    6    2    2    2       467   0.00000      pspcod,pspxc,lmax,lloc,mmax,r2well
  No XC core correction.
  1.024700          amesh (Hamman grid)
pspatm: epsatm=    2.29671063
         --- l  ekb(1:nproj) -->
             0    5.433081
             1   -9.177129
pspatm: atomic psp has been read  and splines computed

   8.77250985E+05                                ecore*ucvol(ha*bohr**3)
--------------------------------------------------------------------------------

P newkpt: treating    612 bands with npw=     397 for ikpt=   1
P newkpt: treating    612 bands with npw=     427 for ikpt=   2
P newkpt: treating    612 bands with npw=     428 for ikpt=   3
P newkpt: treating    612 bands with npw=     424 for ikpt=   4
P newkpt: treating    612 bands with npw=     424 for ikpt=   5
P newkpt: treating    612 bands with npw=     427 for ikpt=   6
P newkpt: treating    612 bands with npw=     428 for ikpt=   7
P newkpt: treating    612 bands with npw=     416 for ikpt=   8
P newkpt: treating    612 bands with npw=     425 for ikpt=   9
P newkpt: treating    612 bands with npw=     424 for ikpt=  10
P newkpt: treating    612 bands with npw=     425 for ikpt=  11
P newkpt: treating    612 bands with npw=     425 for ikpt=  12
P newkpt: treating    612 bands with npw=     425 for ikpt=  13
P newkpt: treating    612 bands with npw=     424 for ikpt=  14

setup2: Arith. and geom. avg. npw (full set) are     424.219     424.184

================================================================================

     iter   Etot(hartree)      deltaE(h)  residm     vres2    diffor    maxfor
ETOT  1   79945.258982940     7.995E+04 2.464E+05 2.542E+06 2.935E+03 2.935E+03
ETOT  2   79469.621528863    -4.756E+02 2.110E+04 5.785E+05 1.294E+01 2.936E+03
ETOT  3   78653.590191668    -8.160E+02 1.563E+04 5.445E+04 1.247E+01 2.937E+03
ETOT  4   78918.354935734      2.648E+02 8.186E+03 2.324E+05 6.089E+00 2.937E+03
ETOT  5   78179.241323848    -7.391E+02 8.937E+03 9.623E+04 1.077E+01 2.936E+03
ETOT  6   77802.807623901    -3.764E+02 1.209E+04 2.750E+05 3.959E+00 2.936E+03
ETOT  7   77129.839980344    -6.730E+02 8.598E+03 8.349E+04 4.584E+00 2.936E+03
ETOT  8   77994.014938850     8.642E+02 8.386E+03 2.130E+04 4.007E+00 2.936E+03
ETOT  9   77500.518845223    -4.935E+02 8.882E+03 1.569E+03 3.102E+00 2.937E+03
ETOT 10   78096.980620950     5.965E+02 1.243E+04 6.659E+02 7.194E-01 2.936E+03
ETOT 11   77919.493905209    -1.775E+02 2.080E+04 1.240E+03 6.896E-01 2.936E+03
ETOT 12   77706.038470941     -2.135E+02 2.026E+04 1.215E+03 6.712E-01 2.936E+03
ETOT 13   78030.482761637     3.244E+02 1.800E+04 1.448E+03 3.102E-01 2.936E+03
ETOT 14   78009.316774054    -2.117E+01 1.444E+04 1.469E+02 6.030E-01 2.936E+03
ETOT 15   78161.558599271     1.522E+02 1.050E+04 3.695E+02 5.366E-01 2.936E+03
ETOT 16   78014.933449950    -1.466E+02 1.475E+04 1.872E+03 9.526E-01 2.936E+03
ETOT 17   77663.228157510    -3.517E+02 1.120E+04 4.153E+02 9.041E-01 2.936E+03
ETOT 18   77989.673584398     3.264E+02 8.906E+03 5.843E+02 5.869E-01 2.936E+03
ETOT 19   78125.103560703     1.354E+02 1.893E+04 3.051E+02 3.721E-01 2.936E+03
ETOT 20   78081.964035634     -4.314E+01 1.298E+05 2.278E+02 4.071E-01 2.936E+03
ETOT 21   78018.379627737    -6.358E+01 7.656E+03 2.526E+02 3.613E-01 2.936E+03
ETOT 22   78153.440485840     1.351E+02 1.007E+04 1.557E+02 2.479E-01 2.936E+03
ETOT 23   77913.371725496    -2.401E+02 2.001E+04 1.305E+02 2.791E-01 2.936E+03
ETOT 24   77768.054225661    -1.453E+02 1.896E+04 5.731E+02 4.618E-01 2.936E+03
ETOT 25   78024.940484314     2.569E+02 7.373E+03 2.126E+02 2.492E-01 2.936E+03
ETOT 26   78033.248243471     8.308E+00 1.294E+04 2.037E+01 3.662E-01 2.936E+03
ETOT 27   78058.909845031     2.566E+01 1.145E+04 2.741E+01 2.541E-01 2.936E+03
ETOT 28   78192.312938657      1.334E+02 1.358E+04 8.235E+01 3.068E-01 2.936E+03
ETOT 29   78008.061218873    -1.843E+02 2.404E+04 1.472E+02 2.886E-01 2.936E+03
ETOT 30   78021.279950688     1.322E+01 2.349E+04 1.020E+02 3.292E-01 2.936E+03
ETOT 31   78229.649791255     2.084E+02 1.499E+04 1.012E+02 4.994E-01 2.936E+03
ETOT 32   77890.221885284    -3.394E+02 1.633E+04 1.381E+01 3.874E-01 2.936E+03
ETOT 33   78085.180801986     1.950E+02 1.651E+04 1.500E+02 5.351E-01 2.936E+03
ETOT 34   78132.611479930     4.743E+01 2.047E+04 1.814E+01 3.740E-01 2.936E+03
ETOT 35   78217.369887135     8.476E+01 1.116E+04 4.319E+01 2.192E-01 2.936E+03
ETOT 36   78303.491989164      8.612E+01 1.815E+04 1.197E+01 3.005E-01 2.936E+03
ETOT 37   78021.899566683    -2.816E+02 1.943E+04 1.589E+01 2.243E-01 2.936E+03
ETOT 38   77850.332565168    -1.716E+02 1.292E+04 1.557E+02 3.916E-01 2.936E+03
ETOT 39   78298.656422974     4.483E+02 2.523E+04 1.014E+02 5.553E-01 2.936E+03
ETOT 40   77947.067269152    -3.516E+02 1.472E+04 2.499E+01 2.945E-01 2.936E+03

Cartesian components of stress tensor (hartree/bohr^3)
  sigma(1 1)= -1.32939546E+05  sigma(3 2)=  0.00000000E+00
  sigma(2 2)= -1.32955170E+05  sigma(3 1)=  0.00000000E+00
  sigma(3 3)= -1.25706814E+05  sigma(2 1)= -4.08500196E-12


scprqt:  WARNING -
  nstep=   40 was not enough SCF cycles to converge;
  potential residual=  2.499E+01 exceeds tolvrs=  1.000E-18

================================================================================

----iterations are completed or convergence reached----

Mean square residual over all n,k,spin=   2.2982E+03; max=  1.4716E+04
   0.0000  0.0000  0.1250    1  1.78639E+02 kpt; spin; max resid(k); each band:
1.51E+02 1.44E+02 1.44E+02 1.66E+02 1.68E+02 1.59E+02 1.53E+02 1.56E+02
1.57E+02 1.58E+02 1.67E+02 1.79E+02 1.63E+02 1.59E+02 1.56E+02 1.55E+02

########################the input file#####################################

#Boron-Nitride Nanotube
#tube length 30A
#bond length 1.42A
#number of atoms 290

#(hexagonal) structure

#Alternative response function calculation for some rigid-atom
#piezoelectric tensor elements (3-3 component).
#C/m^2=57.2147606a.u

   ndtset   3

# Set 1 : Initial self-consistent run

    iscf1   5
  kptopt1   1
  prtden1   1        #second dataset need density
  tolvrs1   1.0d-18  #need excellent convergence of GS quantities for RF runs


#Second dataset : finite-difference d/dk ground-state calculation
#                uses bdberry_new

berryopt2   -2       #specifies ddk wave functions wanted
  getden2   -1       #use density from previous dataset
  getwfk2   -1       #use wave function from profious dataset
  kptopt2   3        #need full set of k points herre
    iscf2   -2       #non-self-consistent
   rfdir2   0 0 1    #we are only checking a c-axis quantity
  tolwfr2   1.0d-20  # only wave function convergence can be used with
                     # non-self-consistent calculation

# Set 3 : response-function calculations for all needed perturbations

  getddk3  -1
  getwfk3  -1
    iscf3   5
  kptopt3   2        #use time-reversal symmetry only for k points
    nqpt3   1
     qpt3   0 0 0
  rfstrs3   1        #do strain perturbation
   rfdir3   0 0 1    #the full set of directions is needed
  tolvrs3   1.0d-10  #need reasonable convergence of 1st-order quantities

#######################################################################
#Common input variables




#Definition of the unit cell (hexagonal lattice)

#Starting approximation for the unit cell

acell  7.5389648144E+00  7.5389648144E+00  1.2277795374E+01

rprim   sqrt(0.75)  0.5  0.0   #hexagonal primitive vectors must be
        -sqrt(0.75)  0.5   0.0   #specified with high accuracy to be
         0.0         0.0  1.0   #sure that the symmetry is recognized
                                 #and preserved in the optimization
                                 #process


#An alternative definition of hexagonal lattice

#acell 2*6.0d0 10.0d0 angstrom   # The keyword "acell" refers to the
                                # lengths of the primitive vectors (in Bohr)
#angdeg 2*90.0d0 120.0d0         #Gives the angles between directions of
                                #primitive vectors of the unit
                                #cell (in degrees)


#Definition of the atom types
ntypat  2        # There are 2 types of atoms
znucl   5 7      # The keyword "znucl" refers to the atomic number of the
                 # possible type(s) of atom. 5 for Bohr and 7 for Nitrogen
                 # The pseudopotential(s)mentioned in the "files" file
                 # must correspond to the type(s) of atom.


#Starting approximation for atomic positions in cartesian coordinates

#Definition of the atoms
natom   290      #number of B & N atoms is 290
typat 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2
1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2
1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2
1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2
1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 2 2 1 1 1 1 1 1 1 1 1 1
xcart             # This keyword indicate that the location of the atoms
                  # will follow, one triplet of number for each atom
                  # Triplet giving the cartesian coordinates of each atom, in Bohr
3.914 0 0
3.723 1.21 2.13
3.914 0 1.42
3.723 1.21 3.55
3.914 0 4.26
3.723 1.21 6.39
3.914 0 5.68
3.723 1.21 7.81
3.914 0 8.52
3.723 1.21 10.65
3.914 0 9.94
3.723 1.21 12.07
3.914 0 12.78
3.723 1.21 14.91
3.914 0 14.2
3.723 1.21 16.33
3.914 0 17.04
3.723 1.21 19.17
3.914 0 18.46
3.723 1.21 20.59
3.914 0 21.3
3.723 1.21 23.43
3.914 0 22.72
3.723 1.21 24.85
3.914 0 25.56
3.723 1.21 27.69
3.914 0 26.98
3.723 1.21 29.11
3.914 0 29.82
3.167 2.301 0
3.167 2.301 1.42
2.301 3.167 3.55
3.167 2.301 4.26
2.301 3.167 6.39
3.167 2.301 5.68
2.301 3.167 7.81
3.167 2.301 8.52
2.301 3.167 10.65
3.167 2.301 9.94
2.301 3.167 12.07
3.167 2.301 12.78
2.301 3.167 14.91
3.167 2.301 14.2
2.301 3.167 16.33
3.167 2.301 17.04
2.301 3.167 19.17
3.167 2.301 18.46
2.301 3.167 20.59
3.167 2.301 21.3
2.301 3.167 23.43
3.167 2.301 22.72
2.301 3.167 24.85
3.167 2.301 25.56
2.301 3.167 27.69
3.167 2.301 26.98
2.301 3.167 29.11
3.167 2.301 29.82
1.21 3.723 0
1.21 3.723 1.42
0 3.914 3.55
1.21 3.723 4.26
0 3.914 6.39
1.21 3.723 5.68
0 3.914 7.81
1.21 3.723 8.52
0 3.914 10.65
1.21 3.723 9.94
0 3.914 12.07
1.21 3.723 12.78
0 3.914 14.91
1.21 3.723 14.2
0 3.914 16.33
1.21 3.723 17.04
0 3.914 19.17
1.21 3.723 18.46
0 3.914 20.59
1.21 3.723 21.3
0 3.914 23.43
1.21 3.723 22.72
0 3.914 24.85
1.21 3.723 25.56
0 3.914 27.69
1.21 3.723 26.98
0 3.914 29.11
1.21 3.723 29.82
-1.21 3.723 0
-1.21 3.723 1.42
-2.301 3.167 3.55
-1.21 3.723 4.26
-2.301 3.167 6.39
-1.21 3.723 5.68
-2.301 3.167 7.81
-1.21 3.723 8.52
-2.301 3.167 10.65
-1.21 3.723 9.94
-2.301 3.167 12.07
-1.21 3.723 12.78
-2.301 3.167 14.91
-1.21 3.723 14.2
-2.301 3.167 16.33
-1.21 3.723 17.04
-2.301 3.167 19.17
-1.21 3.723 18.46
-2.301 3.167 20.59
-1.21 3.723 21.3
-2.301 3.167 23.43
-1.21 3.723 22.72
-2.301 3.167 24.85
-1.21 3.723 25.56
-2.301 3.167 27.69
-1.21 3.723 26.98
-2.301 3.167 29.11
-1.21 3.723 29.82
-3.167 2.301 0
-3.167 2.301 1.42
-3.723 1.21 3.55
-3.167 2.301 4.26
-3.723 1.21 6.39
-3.167 2.301 5.68
-3.723 1.21 7.81
-3.167 2.301 8.52
-3.723 1.21 10.65
-3.167 2.301 9.94
-3.723 1.21 12.07
-3.167 2.301 12.78
-3.723 1.21 14.91
-3.167 2.301 14.2
-3.723 1.21 16.33
-3.167 2.301 17.04
-3.723 1.21 19.17
-3.167 2.301 18.46
-3.723 1.21 20.59
-3.167 2.301 21.3
-3.723 1.21 23.43
-3.167 2.301 22.72
-3.723 1.21 24.85
-3.167 2.301 25.56
-3.723 1.21 27.69
-3.167 2.301 26.98
-3.723 1.21 29.11
-3.167 2.301 29.82
-3.914 0 0
-3.914 0 1.42
-3.723 -1.21 3.55
-3.914 0 4.26
-3.723 -1.21 6.39
-3.914 0 5.68
-3.723 -1.21 7.81
-3.914 0 8.52
-3.723 -1.21 10.65
-3.914 0 9.94
-3.723 -1.21 12.07
-3.914 0 12.78
-3.723 -1.21 14.91
-3.914 0 14.2
-3.723 -1.21 16.33
-3.914 0 17.04
-3.723 -1.21 19.17
-3.914 0 18.46
-3.723 -1.21 20.59
-3.914 0 21.3
-3.723 -1.21 23.43
-3.914 0 22.72
-3.723 -1.21 24.85
-3.914 0 25.56
-3.723 -1.21 27.69
-3.914 0 26.98
-3.723 -1.21 29.11
-3.914 0 29.82
-3.167 -2.301 0
-3.167 -2.301 1.42
-2.301 -3.167 3.55
-3.167 -2.301 4.26
-2.301 -3.167 6.39
-3.167 -2.301 5.68
-2.301 -3.167 7.81
-3.167 -2.301 8.52
-2.301 -3.167 10.65
-3.167 -2.301 9.94
-2.301 -3.167 12.07
-3.167 -2.301 12.78
-2.301 -3.167 14.91
-3.167 -2.301 14.2
-2.301 -3.167 16.33
-3.167 -2.301 17.04
-2.301 -3.167 19.17
-3.167 -2.301 18.46
-2.301 -3.167 20.59
-3.167 -2.301 21.3
-2.301 -3.167 23.43
-3.167 -2.301 22.72
-2.301 -3.167 24.85
-3.167 -2.301 25.56
-2.301 -3.167 27.69
-3.167 -2.301 26.98
-2.301 -3.167 29.11
-3.167 -2.301 29.82
-1.21 -3.723 0
-1.21 -3.723 1.42
0 -3.914 3.55
-1.21 -3.723 4.26
0 -3.914 6.39
-1.21 -3.723 5.68
0 -3.914 7.81
-1.21 -3.723 8.52
0 -3.914 10.65
-1.21 -3.723 9.94
0 - 3.914 12.07
-1.21 -3.723 12.78
0 -3.914 14.91
-1.21 -3.723 14.2
0 -3.914 16.33
-1.21 -3.723 17.04
0 -3.914 19.17
-1.21 -3.723 18.46
0 -3.914 20.59
-1.21 -3.723 21.3
0 -3.914 23.43
-1.21 -3.723 22.72
0 -3.914 24.85
-1.21 -3.723 25.56
0 -3.914 27.69
-1.21 -3.723 26.98
0 -3.914 29.11
-1.21 -3.723 29.82
1.21 -3.723 0
1.21 -3.723 1.42
2.301 -3.167 3.55
1.21 -3.723 4.26
2.301 -3.167 6.39
1.21 -3.723 5.68
2.301 -3.167 7.81
1.21 -3.723 8.52
2.301 -3.167 10.65
1.21 -3.723 9.94
2.301 -3.167 12.07
1.21 -3.723 12.78
2.301 -3.167 14.91
1.21 -3.723 14.2
2.301 -3.167 16.33
1.21 -3.723 17.04
2.301 -3.167 19.17
1.21 -3.723 18.46
2.301 -3.167 20.59
1.21 -3.723 21.3
2.301 -3.167 23.43
1.21 -3.723 22.72
2.301 -3.167 24.85
1.21 -3.723 25.56
2.301 -3.167 27.69
1.21 -3.723 26.98
2.301 -3.167 29.11
1.21 -3.723 29.82
3.167 -2.301 0
3.167 -2.301 1.42
3.723 -1.21 3.55
3.167 -2.301 4.26
3.723 -1.21 6.39
3.167 -2.301 5.68
3.723 -1.21 7.81
3.167 -2.301 8.52
3.723 - 1.21 10.65
3.167 -2.301 9.94
3.723 -1.21 12.07
3.167 -2.301 12.78
3.723 -1.21 14.91
3.167 -2.301 14.2
3.723 -1.21 16.33
3.167 -2.301 17.04
3.723 -1.21 19.17
3.167 -2.301 18.46
3.723 -1.21 20.59
3.167 -2.301 21.3
3.723 -1.21 23.43
3.167 -2.301 22.72
3.723 -1.21 24.85
3.167 -2.301 25.56
3.723 -1.21 27.69
3.167 -2.301 26.98
3.723 -1.21 29.11
3.167 -2.301 29.82
2.301 3.167 2.13
-2.301 -3.167 2.13
0 -3.914 2.13
-3.723 -1.21 2.13
0 3.914 2.13
-2.301 3.167 2.13
-3.723 1.21 2.13
2.301 -3.167 2.13
3.723 -1.21 2.13

#Gives the number of band, explicitely (do not take the default)
#nband  8               # For an insulator (if described correctly as an insulator
                       # by DFT), there is no need to include conduction bands
                       # in response-function calculations

#Exchange-correlation functional
ixc 2             #  LDA, Perdew-Zunger-Ceperley-Alder (no spin-polarization)



#Definition of the planewave basis set
ecut   6.0              # Maximum kinetic energy cutoff (Hartree)
ecutsm   0.5            # Smoothing energy needed for lattice paramete
                         # optimization.  This will be retained for
                         # consistency throughout.
#Definition of the k-point grid
kptopt   1               # Use symmetry and treat only inequivalent points
ngkpt   4 4 4            # 4x4x4 Monkhorst-Pack grid
nshiftk   1              # Use one copy of grid only (default)
shiftk   0.0 0.0 0.5     # This choice of origin for the k point grid
                         # preserves the hexagonal symmetry of the grid,
                         # which would be broken by the default choice.


#Definition of the SCF procedure
diemac   9.0             # Model dielectric preconditioner
nstep   40               # Maxiumum number of SCF iterations
iscf   5                 # Use conjugate-gradient SCF cycle
#tolvrs   1.0d-18         # Strict tolerance on (squared) residual of the
                         # SCF potential needed for accurate forces and
                         # stresses in the structural optimization, and
                         # accurate wave functions in the RF calculations

-- 
Pierre-Matthieu Anglade