[Pw_forum] Symmetry problem in Ge and phonon calculation problem in InP

[Ashutosh Kumar]

Dear pwscf users

I've been trying to do phonon calculations, for elemental and compound semiconductors(Si, Ge, InP and SiC). Si and Ge both have exactly the same structure and space group, so symmetry operations are also same. Below is the self consistent input file, i'm using. In case of Si and Ge, the scf.out file works with all the 48 symmetry operations but in case of Ge it rejects all the inversion symmetry opertors. Also, for further calculations i'm using exactly the procedure given in example07 directory.

Also, for InP, I used the same procedure, but i'm missing the splitting of phonon spectra at higher frequency, as reported in publications. After going through the forums, I got to know that I should use zasr=.true. and epsil=.true. for calculations in InP, since it is a polar semiconductor. I tried this and the phonon calculation job keeps on crashing. I don't understand what should I do to solve this problem?


 &control
    calculation='scf'
    restart_mode='from_scratch',
    prefix='ge',
    pseudo_dir = '/nfs/18/osu5465/espresso/espresso-3.2/pseudo/',
    outdir='/nfs/18/osu5465/espresso/tmp/'
 /
 &system
    ibrav= 2, celldm(1) =10.691, nat=2 , ntyp= 1,
    ecutwfc =25.0,
    occupations='smearing', smearing='methfessel-paxton', degauss=0.05,
 /
 &electrons
    conv_thr =  1.0d-8
    mixing_beta = 0.7
 /
ATOMIC_SPECIES
 Ge  72.61   Ge.pz-bhs.UPF
ATOMIC_POSITIONS {crystal}
Ge     0.250000  0.250000    0.25000000
Ge     0.000000  0.000000    0.00000000
K_POINTS {automatic}
 8 8 8 0 0 0

--
Ashutosh Kumar
Grad Student
The Ohio State University
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