[Pw_forum] Phonon of single layer MoS2

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Dear all:

I am calculating phonons of singel-layer MoS2 (SLMoS2). I have two confusions here.

First is usually it takes me two days to complete the phonon calculation for just 3 atom unit cell of SLMoS2. I am wondering if any settings in my input file is too high like some threshold, but no idea why it takes so long. I have attached  the scf.in and phonon.in file for scf calculation below.

The second is do I have to include smearing in the scf calculation? Does it have large influence on the results? Since it takes too long to calculate I have not got the chance to try, anyone has similar experience willing to give me some advice here? I will be very appreciated, thanks.

scf.in:
&control
    calculation='scf',
    restart_mode='from_scratch',
    nstep=50
    tstress = .true.
    tprnfor = .true.
    prefix='SLMoS2',
    pseudo_dir='/home/jpeng/Downloads/espresso-5.2.0/mypotential/'
    outdir='/home/jpeng/Downloads/espresso-5.2.0/tmpdir/',
 /
 &system
    ibrav= 0,
    A=3.192,
    nat=  3, ntyp= 2,
/
 &electrons
    conv_thr=1e-10
    mixing_beta = 0.7
/
CELL_PARAMETERS
1.0 0.0 0.0
0.5 0.866 0.0
0.0 0.0 10
ATOMIC_SPECIES
 Mo  95.94  Mo.pbe-spn-kjpaw_psl.0.2.UPF
 S  32.065  S.pbe-n-kjpaw_psl.0.1.UPF
ATOMIC_POSITIONS (crystal)
Mo 2/3 2/3 0.04907565
S 1/3 1/3 0
S 1/3 1/3 0.0981513
K_POINTS automatic
6 6 6 1 1 1

phonon.in:
phonons of SLMoS2
 &inputph
  tr2_ph=1.0d-12,
  prefix='SLMoS2',
  ldisp=.true
  nq1=4
  nq2=4
  nq3=4
  amass(1)=95.94,
  amass(2)=32.065,
  fildyn='SLMoS2.dyn',
  outdir='/home/jpeng/Downloads/espresso-5.2.0/tmpdir/'
 /

Best
Jie Peng
PhD student
University of Maryland