Too possible reasons:
You did not do convergence test, in
fact you should not only test the energy, but also other quanlties
that concerns your results
Your cell structure is not well optimized
so it is unstable, you should optimized it to ground state
-----Original
Message-----
From: Lee Geunsik
[mailto:maxgeun@postech.ac.kr]
Sent: 2004年5月30日
15:03
To: forum@abinit.org
Subject: [abinit-forum] strange
phonon band structure for Si
I have calculated
IFCs of Si for 4x4x4, 6x6x6, 8x8x8 q-mesh.
Also I drawed
phonon band structure.
The result is
strikingly different as I increase q-mesh.
I attach the band
structure file, "test.ps".
Followings are
related input files for abinit, anaddb.
------------------
input file for abinit ------------------
#Ground state
kptopt1 1
tolvrs1 1.0d-18
iscf1 5
prtden1 1
#Non-self consistent
ground-state, with general q
nqpt2 1
getwfk2 1
getden2 1
kptopt2 3
tolwfr2 1.0d-18
iscf2 -2
#Response function with general q
rfphon3 1
rfatpol3 1 2
rfdir3 1 1 1
nqpt3 1
getwfk3 1
getwfq3 2
kptopt3 3
tolvrs3 1.0d-8
iscf3 5
#Non-self
consistent ground-state, with general q
nqpt4 1
getwfk4 1
getden4 1
kptopt4 3
tolwfr4 1.0d-18
iscf4 -2
#Response function with general q
rfphon5 1
rfatpol5 1 2
rfdir5 1 1 1
nqpt5 1
getwfk5 1
getwfq5 4
kptopt5 3
tolvrs5 1.0d-8
iscf5 5
.....
qpt2
0.00000000E+00 0.00000000E+00 0.00000000E+00
qpt3
0.00000000E+00 0.00000000E+00 0.00000000E+00
qpt4
2.50000000E-01 0.00000000E+00 0.00000000E+00
qpt5
2.50000000E-01 0.00000000E+00 0.00000000E+00
qpt6
5.00000000E-01 0.00000000E+00 0.00000000E+00
qpt7
5.00000000E-01 0.00000000E+00 0.00000000E+00
qpt8
2.50000000E-01 2.50000000E-01 0.00000000E+00
qpt9
2.50000000E-01 2.50000000E-01 0.00000000E+00
qpt10
5.00000000E-01 2.50000000E-01 0.00000000E+00
qpt11
5.00000000E-01 2.50000000E-01 0.00000000E+00
qpt12
-2.50000000E-01 2.50000000E-01 0.00000000E+00
qpt13
-2.50000000E-01 2.50000000E-01 0.00000000E+00
qpt14
5.00000000E-01 5.00000000E-01 0.00000000E+00
qpt15
5.00000000E-01 5.00000000E-01 0.00000000E+00
qpt16
-2.50000000E-01 5.00000000E-01 2.50000000E-01
qpt17
-2.50000000E-01 5.00000000E-01 2.50000000E-01
#######################################################################
#Common input variables
#Definition of the
unit cell
acell 3*10.166 # This is
equivalent to 10.18 10.18 10.18
rprim 0.0 0.5 0.5 # FCC primitive vectors (to be
scaled by acell)
0.5 0.0 0.5
0.5 0.5 0.0
#Definition of the
atom types
ntypat 1 # There is only
one type of atom
znucl 14 # The keyword
"znucl" refers to the atomic number of the
# possible type(s) of atom. The pseudopotential(s)
# mentioned in the "files" file must correspond
# to the type(s) of atom. Here, the only type is Silicon.
#Definition of the atoms
natom 2 # There are
two atoms
typat 1 1 # They both are of
type 1, that is, Silicon.
xred
# This keyword indicate that the location of the atoms
# will follow, one triplet of number for each atom
0.0 0.0 0.0 # Triplet giving the REDUCED
coordinate of atom 1.
1/4 1/4 1/4 # Triplet giving the REDUCED
coordinate of atom 2.
#Definition of the
planewave basis set
ecut 10.0 # Maximal
kinetic energy cut-off, in Hartree
#Definition of the
k-point grid
ngkpt 8 8 8
nshiftk 1
shiftk 0.5 0.5 0.5
#Definition of the
SCF procedure
nstep 20 # Maximal number
of SCF cycles
diemac 12.0
------------------
input file for anaddb ------------------
!Flags
ifcflag 1 ! Interatomic force
constant flag
!Effective charges
asr 1 ! Acoustic
Sum Rule. 1 => imposed asymetrically
!Interatomic force
constant info
dipdip 0 ! Dipole-dipole interaction
treatment
ifcana 1 ! Analysis of the IFCs
ifcout 20 ! Number of IFC's written in the
output, per atom
natifc 1 ! Number of atoms in the
cell for which ifc's are analysed
atifc 1 ! List of atoms
!Wavevector grid
number 1 (coarse grid, from DDB)
brav 2 ! Bravais Lattice
: 1-S.C., 2-F.C., 3-B.C., 4-Hex.)
ngqpt 4 4 4 ! Monkhorst-Pack indices
nqshft 1 ! number
of q-points in repeated basic q-cell
q1shft 0.0 0.0 0.0
!Wavevector list
number 1 (Reduced coordinates and normalization factor)
nph1l 61 ! number of
phonons in list 1
qph1l 0.0 0.0 0.0 1 ! Gamma
0.075 0.0375 0.0375 1
0.150 0.0750 0.0750 1
0.225 0.1125 0.1125 1
0.300 0.1500 0.1500 1
0.375 0.1875 0.1875 1
0.450 0.2250 0.2250 1
0.525 0.2625 0.2625 1
0.600 0.3000 0.3000 1
0.675 0.3375 0.3375 1
0.625 0.25 0.625 1 ! K
0.6000 0.2000 0.6000 1
0.5750 0.1500 0.5750 1
0.5500 0.1000 0.5500 1
0.5250 0.0500 0.5250 1
0.5 0.0 0.5 1
! X
0.450 0.0000 0.4500 1
0.400 0.0000 0.4000 1
0.350 0.0000 0.3500 1
0.300 0.0000 0.3000 1
0.250 0.0000 0.2500 1
0.200 0.0000 0.2000 1
0.150 0.0000 0.1500 1
0.100 0.0000 0.1000 1
0.050 0.0000 0.0500 1
0.0 0.0 0.0 1
! Gamma
0.050 0.0500 0.0500 1
0.100 0.1000 0.1000 1
0.150 0.1500 0.1500 1
0.200 0.2000 0.2000 1
0.250 0.2500 0.2500 1
0.300 0.3000 0.3000 1
0.350 0.3500 0.3500 1
0.400 0.4000 0.4000 1
0.450 0.4500 0.4500 1
0.5 0.5 0.5 1
! L
0.500 0.4500 0.5000 1
0.500 0.4000 0.5000 1
0.500 0.3500 0.5000 1
0.500 0.3000 0.5000 1
0.500 0.2500 0.5000 1
0.500 0.2000 0.5000 1
0.500 0.1500 0.5000 1
0.500 0.1000 0.5000 1
0.500 0.0500 0.5000 1
0.5 0.0 0.5 1 ! X
0.550 0.0500 0.5000 1
0.600 0.1000 0.5000 1
0.650 0.1500 0.5000 1
0.700 0.2000 0.5000 1
0.75 0.25 0.5 1 ! W
0.725 0.2750 0.5000 1
0.700 0.3000 0.5000 1
0.675 0.3250 0.5000 1
0.650 0.3500 0.5000 1
0.625 0.3750 0.5000 1
0.600 0.4000 0.5000 1
0.575 0.4250 0.5000 1
0.550 0.4500 0.5000 1
0.525 0.4750 0.5000 1
0.5 0.5 0.5 1 ! L
