The ABINIT Users Mailing List ( CLOSED )

[spizzinato@icp.csic.es]

Dear all,

I'm just beginning my experience with abinit and I would like to know how to 
obtain thermodynamic properties from phonon results. I have tried with anaddb 
but I think I do something wrong because it doesn't give me any free energy, 
entropy, constant volume heat capacity  values nor trend with temperature.

The system I'm studying is GaAs.

Well, I do a calculation of phonon frequencies with abinip that results quite 
well and then I merge the DDBs with mrgddb.

And then I try to calculate thermodynamic properties with anaddb. I send you 
the input file of anaddb that I use, maybe someone could kindly tell me what 
I do wrong.
------------------------------------------------------------------------------
!Flags
 ifcflag   1     ! Interatomic force constant flag
 thmflag   1     ! Thermal flag. Gives Internal energy, entropy,
 dieflag   1     ! Frequency-dependent Dielectric tensor flag                

!Effective charges
     asr   1     ! Acoustic Sum Rule. 1 => imposed asymetrically
 chneut    2
 enunit    0

!Interatomic force constant info
  dipdip  1      ! Dipole-dipole interaction treatment
  ifcana  1      ! Analysis of the IFCs
  ifcout  3      ! Number of IFC's written in the output, per atom
  natifc  2      ! Number of atoms in the cell for which ifc's are analysed
 atifc  1 2      ! List of atoms
  

#!Thermal information
 nchan   1250   ! # of channels for the DOS with channel width 1 cm-1
 nwchan  5      ! # of different channel widths from this integer down to 1 cm
 thmtol  0.060  ! Tolerance on thermodynamical function fluctuations
 ntemper 10     ! Number of temperatures    
 temperinc 5    ! Increment of temperature in K for temperature dependency    
 tempermin 300   ! Minimal temperature in Kelvin
dostol    0.25

#!Wavevector grid number 1 (coarse grid, from DDB)
  brav    3         ! 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 grid number 2
   ng2qpt   4 4 4  ! sample the BZ up to ngqpt2
  ngrid  4         ! number of grids of increasing size
  q2shft   0.5  0.5  0.5  

!Wavevector list number 1 (Reduced coordinates and normalization factor)      
   
  nph1l    6       ! number of phonons in list 1                              
 
  qph1l     0.0  0.0  0.0    1.0   ! (G point)
            0.5  0.0  0.0    1.0   ! (L point)
            0.5  0.5  0.0    1.0   ! (X point)
            0.5  0.5  0.5    1.0   ! (L point again)
            0.25 0.25 0.25   1.0
            0.25 0.5  0.5    1.0

!Wavevector list number 2 (Gamma point only, with limiting direction          
   
!           in cartesian coordinates. )                                       
   
  nph2l  3         ! number of phonons in list 2                              
 
  qph2l  0.0 0.0 0.1    0.0
         0.1 0.0 0.0    0.0
         0.0 0.0 0.1    0.0

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

So thank you very very much.

Sara Pizzinato
PhD student 
Instituto de Catálisis y Petroleoquímica -CSIC- Madrid