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 / ari.p.seitso...@iki.fi / 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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