The ABINIT Users Mailing List ( CLOSED )

[Masatake Takahashi <masatake@iis.u-tokyo.ac.jp>]

Dear ABINIT users.

Recent days, I have a convergence problem with PAW potential.
I want to perform ground state calculations
of perovskite type ferroelectric PbTiO3
with ABINIT 4.2.3 (for Windows).

I have tested various parameters sets (ecut, pawecutdg, pawlcutd, nstep...),
but I was not able to obtain enough convergence.

Could someone give me helpful suggestions ?

Followig lines are my input file and 
a part of the output file.

I made this input file using an example from 
"t04.in" in the test directroy for version 4.

PAW potential files which I used in this calculations
are ones distributed on ABINIT web site,
Vanderbilt's LDA-USPP potentials: Pb, Ti and O.

INPUT file
############################
# 1-PAW options:
# ---------------------
  pawecutdg 400 eV
  pawmqgrdg -1
  pawntheta 12 pawnphi 13
  pawlcutd 5

# 2-Options for output:
# ---------------------
  prtdos 0 
  prtwf 1
  prtden 1

# 3-Parameters governing the convergence:
# ---------------------------------------
  ecut 400 eV
  nband 30
  nstep 20
  toldfe 1.0d-5 eV

# 4-Options for the choice of calculation:
# ----------------------------------------
  ixc 2  occopt 7  tsmear 0.01 eV
  optcell 0  ionmov 0
  ortalg 2
  nline 5
  iscf 5

# 5-Definition of the unit cell:
# ------------------------------
#  chkprim 0

  acell 3*3.96 angstrom

  natom 5  ntypat 3
  typat 1 2 3 3 3
  znucl 82 22 8
  xred 0.0 0.0 0.0
       0.5 0.5 0.5
       0.5 0.5 0.0
       0.5 0.0 0.5
       0.0 0.5 0.5


  
# 6-Definition of K-points :
# --------------------------

  kptopt 1
 ngkpt 4 4 4

#################################################


OUTPUT
    iter   Etot(hartree)      deltaEtot 
ETOT  1  -140.32234867022     -1.403E+02
ETOT  2  -143.66266972979     -3.340E+00
ETOT  3  -144.34620078032     -6.835E-01
ETOT  4  -144.70548353308     -3.593E-01
ETOT  5  -144.35985242057      3.456E-01
ETOT  6  -144.28474448121      7.511E-02
ETOT  7  -144.89400503374     -6.093E-01
ETOT  8  -144.73034823819      1.637E-01
ETOT  9  -144.65283036993      7.752E-02
ETOT 10  -144.90766576070     -2.548E-01
ETOT 11  -144.93120797197     -2.354E-02
ETOT 12  -144.93555211190     -4.344E-03
ETOT 13  -144.69409047090      2.415E-01
ETOT 14  -144.86916873557     -1.751E-01
ETOT 15  -144.98744226368     -1.183E-01
ETOT 16  -145.02165848108     -3.422E-02
ETOT 17  -145.01621033801      5.448E-03
ETOT 18  -145.04750165495     -3.129E-02
ETOT 19  -144.99289528032      5.461E-02
ETOT 20  -145.06607294973     -7.318E-02

###############################################


With Best regards.

Masatake Takahashi