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["Lee Geunsik" <maxgeun@postech.ac.kr>]

Dear Rongqin,

 

Thanks for your attention.

Regarding your opinion, I checked phonon frequencies with one q point, for which has large deviation as I increase q-mesh.

Following is input file.

 

----------------------------------------------------------------------

ndtset 3

 

#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

 

qpt2                0.250 0.2500 0.2500    # 30-th q-point in previous phonon band structure.
qpt3                0.250 0.2500 0.2500  
#######################################################################
#Common input variables

 

...same as previous input parameters....

 

--------------------- end of input file --------------------------------------------

 

Output frequencies are

 

  Phonon wavevector (reduced coordinates) :  0.25000  0.25000  0.25000
 Phonon energies in Hartree :
   4.133144E-04  4.133144E-04  1.049657E-03  2.210757E-03  2.261707E-03
   2.261707E-03
 Phonon frequencies in cm-1    :
-  9.071203E+01  9.071203E+01  2.303730E+02  4.852050E+02  4.963873E+02
-  4.963873E+02

The result is acceptable.

When I do interpolation with anaddb, it gives wrong results.

What did I miss with anaddb?

Thanks.

 

Best regards,

Geunsik.

 

 

----- Original Message -----

From: Wu Rongqin

To: forum@abinit.org

Sent: Sunday, May 30, 2004 5:30 PM

Subject: {SPAM?} RE: [abinit-forum] strange phonon band structure for Si

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

 

Dear all,

 

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.

What's wrong with me?

 

Best regards,

Geunsik.

 

------------------ input file for abinit ------------------

ndtset 17

 

#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.

 

nband 4

ixc 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

 

 enunit   2

 

!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