Dear Sohail Ahmad,
Did you treat the LO-TO splitting? The material seems to have very large
splitting, in the article that you cite 335 cm-1, even if the band gap
is very small. If not, you can see for example the end of
http://people.sissa.it/~degironc/QE-Tutorial/tutorial_phon.htm
on how to calculate that with QE/pw.x+ph.x.
Greetings from Paris,
apsi
-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-
Ari Paavo Seitsonen / [email protected] / http://www.iki.fi/~apsi/
Ecole Normale Supérieure (ENS), Département de Chimie, Paris
Mobile (F) : +33 789 37 24 25 (CH) : +41 79 71 90 935
On Sat, 23 Apr 2016, Sohail Ahmad wrote:
Dear All,
I am trying to calculate phonon frequencies of ScN,
but i am not getting as reported by Prof Umesh Waghmare group
Journal of Applied Physics, 107, 03715 (2010)
Electronic structure, phonons and thermal properties of ScN, ZrN and HfN
I am not getting any frequency around 600 cm-1.
Pls check and suggest any mistakes
-----------------------------------------------------------------------------
Output (and input )of my calculation at Gamma for ScN is as follows
q = ( 0.000000000 0.000000000 0.000000000 )
**************************************************************************
freq ( 1) = 0.073720 [THz] = 2.459027 [cm-1]
freq ( 2) = 0.312948 [THz] = 10.438836 [cm-1]
freq ( 3) = 0.312948 [THz] = 10.438836 [cm-1]
freq ( 4) = 10.407119 [THz] = 347.144126 [cm-1]
freq ( 5) = 10.472361 [THz] = 349.320372 [cm-1]
freq ( 6) = 10.472361 [THz] = 349.320372 [cm-1]
**************************************************************************
Mode symmetry, C_3v (3m) point group:
freq ( 1 - 1) = 2.5 [cm-1] --> A_1 L_1 I+R
freq ( 2 - 3) = 10.4 [cm-1] --> E L_3 I+R
freq ( 4 - 4) = 347.1 [cm-1] --> A_1 L_1 I+R
freq ( 5 - 6) = 349.3 [cm-1] --> E L_3 I+R
--------------------------------------------------------------------------------------
&SYSTEM
ibrav=2,
a=4.501,
nat=2, ntyp=2,
ecutwfc = 250, ecutrho = 1000,
nbnd=15,
occupations = 'smearing', smearing = 'gaussian', degauss = 0.001,
nspin = 2,
starting_magnetization(1)=0.1d0,
/
&ELECTRONS
conv_thr = 1.0d-9,
mixing_beta = 0.3,
/
ATOMIC_SPECIES
Sc 44.956 Sc.pw91-nsp-van.UPF
N 14.007 N.pw91-van_ak.UPF
ATOMIC_POSITIONS {angstrom}
Sc -0.044377705 -0.044377705 -0.044377705
N 2.294877705 2.294877705 2.294877705
K_POINTS automatic
12 12 12 1 1 1
--------------------------------------------------------------------
&inputph
tr2_ph = 1.0d-16,
amass(1) = 44.956,
amass(2) = 14.007,
prefix = 'ScN',
!epsil=.true., ! set this to true for polar semiconductors !
outdir = '/scratch/ScN-scf-30591'
fildyn = 'ScN.dynG',
/
0.0 0.0 0.0
---------------------------------------------------------------------
Dr. Sohail Ahmad
King Khalid UniversityAbha, Saudi Arabia
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