[Pw_forum] jagged phonon dispersion in graphene

[Elie Moujaes]

Dear all,

 

Hope you are all doing fine.  I am computing the phono dispersion in graphene. I am using 1000 points in the matdyn.in file and I used an 8x 8 x 1 grid but I get a jagged dispersion spectrum. I tried even using a 16 x16 x1 grid but almost got the same jagged results..I am not sure why this happening. You will find attached the ps graph of the dispersion. Below are all the input files. Thanks for your help in advance.

 

SCF calculation:

 

control
    prefix='phmonog',
    calculation='scf',
    restart_mode='from_scratch',
    pseudo_dir = '/exp/home/caiapo/emoujaes/espresso/espresso-4.1.3/pseudo/',
    outdir='/exp/home/caiapo/emoujaes/espresso/Moujaes-Results/'
 /
 &system    
    ibrav=  4, celldm(1) =4.608737, celldm(3)=4.53666, nat=2, ntyp= 1,
    ecutwfc = 60.D0, nosym=.true.,occupations='smearing', smearing='XYZ', degauss=0.01, nelec=8
/
 &electrons
    conv_thr=1.D-8,     
    mixing_beta=0.1D0,
    mixing_mode='local-TF'
 /
ATOMIC_SPECIES
 C  12.00000  C.pz-rrkjus.UPF
ATOMIC_POSITIONS crystal
 C 0.000000  0.000000 0.000000 1 1 1 
 C 0.333333  -0.33333 0.000000 1 1 1 
K_POINTS automatic
25 25 1 0 0 0
 

Ph.in file:

 

Phonon dispersion for monographene
 &inputph
  tr2_ph=1.0d-12,
  prefix='phmonog',
  ldisp=.true.,
  lnscf=.true.,
  nq1=16, nq2=16, nq3=1
  amass(1)=12.00,
  outdir='/exp/home/caiapo/emoujaes/espresso/Moujaes-Results/',
  fildyn='phmgraphene.dyn',
/
 
q2r file:
 
 &input
 fildyn = 'phmgraphene.dyn',
 zasr = 'crystal' ,
 flfrc = 'mgraph16160.fc'
/
 
matdyn.in file :
 
&input
 asr = 'crystal',
 amass(1) = 12.00 ,
 flfrc = 'mgraph16160.fc',
 flfrq = 'mgraph16160.freq',
/
1000
  0.00000000  0.00000000  0.00000000  1.000000e-03 
  0.00000000  0.00000000  0.10000000  1.000000e-03 
  0.00000000  0.00000000  0.20000000  1.000000e-03 
  0.00000000  0.00000000  0.30000000  1.000000e-03 
  0.00000000  0.00000000  0.40000000  1.000000e-03 
  0.00000000  0.00000000  0.50000000  1.000000e-03 
  0.00000000  0.00000000  0.60000000  1.000000e-03 
  0.00000000  0.00000000  0.70000000  1.000000e-03 
   .........................
 
 		 	   		  
_________________________________________________________________
http://clk.atdmt.com/UKM/go/195013117/direct/01/
We want to hear all your funny, exciting and crazy Hotmail stories. Tell us now
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20100512/813fecad/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: mgraph16160.bands.ps
Type: application/postscript
Size: 19751 bytes
Desc: not available
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20100512/813fecad/attachment.ps>