[Pw_forum] calculation does not converge

lung Fermin ferminlung at gmail.com
Mon Oct 26 03:50:39 CET 2015


Dear all,

I want to calculate the phonon bands of a material with rhombohedral
structure using phonopy and QE as the force calculator. I first did a
vc-relaxation and obtain the following structure
==== vcrelax.out ===========
CELL_PARAMETERS (alat= 10.03700000)
   0.483245254  -0.279001778   0.825350540
   0.000000000   0.558003555   0.825350540
  -0.483245254  -0.279001778   0.825350540

ATOMIC_POSITIONS (crystal)
Li       0.250000000   0.250000000   0.250000000
Li       0.750000000   0.750000000   0.750000000
Os       0.000000000   0.000000000   0.000000000
Os       0.500000000   0.500000000   0.500000000
O        0.623428459   0.876571541   0.250000000
O        0.376571541   0.123428459   0.750000000
O        0.876571541   0.250000000   0.623428459
O        0.123428459   0.750000000   0.376571541
O        0.250000000   0.623428459   0.876571541
O        0.750000000   0.376571541   0.123428459
End final coordinates
=============================
As phonopy requires the cell parameters to be in the Bohr unit. I
multiplied the above CELL_PARAMETERS by the lattice constant 10.037. Then
using phonopy, a 2x2x2 supercell is created. I tried to calculate the force
in QE for one of the displaced supercells but the calculation does not
converge even after 200 cycles. I also tried to reduce the mixing beta but
it didn't help. The following is the input file
===== 001.in ==================
  &control
    calculation='scf',
    restart_mode='from_scratch',
    prefix='001',
    outdir = './tmp/',
    pseudo_dir =
'/home/QE/espresso-5.1.2/pslibrary.1.0.0/pbe/PSEUDOPOTENTIALS/',
    max_seconds = 172000
    wf_collect = .false.
 /
 &system
    nat = 80
    ntyp = 3
    ibrav = 0
    ecutwfc =60
    ecutrho=480
 /
 &electrons
   mixing_beta=0.3D0,
    conv_thr=1.D-8
    electron_maxstep=200
 /
 &ions
 /
&cell
 /
K_POINTS AUTOMATIC
4 4 4 0 0 0
CELL_PARAMETERS bohr
    9.7006599999999992   -5.6006799999999997   16.5680799999999984
    0.0000000000000000   11.2013599999999993   16.5680799999999984
   -9.7006599999999992   -5.6006799999999997   16.5680799999999984
ATOMIC_SPECIES
 Li    6.94100   Li.pbe-s-rrkjus_psl.1.0.0.UPF
 Os  190.23000   Os.pbe-spn-rrkjus_psl.1.0.0.UPF
  O   15.99940   O.pbe-n-rrkjus_psl.1.0.0.UPF
ATOMIC_POSITIONS crystal
 Li   0.1260000353821472  0.1250000000000000  0.1250000000000000
 Li   0.6249999999999999  0.1250000000000000  0.1250000000000000
 Li   0.1250000000000000  0.6250000000000000  0.1250000000000000
 Li   0.6250000000000000  0.6250000000000000  0.1250000000000000
 Li   0.1249999999999999  0.1249999999999999  0.6250000000000000
 Li   0.6249999999999999  0.1249999999999999  0.6250000000000000
 Li   0.1249999999999999  0.6249999999999999  0.6250000000000000
 Li   0.6249999999999998  0.6249999999999999  0.6249999999999999
 Li   0.3749999999999999  0.3750000000000000  0.3750000000000000
 Li   0.8749999999999999  0.3749999999999999  0.3750000000000000
 Li   0.3749999999999999  0.8750000000000000  0.3749999999999999
 Li   0.8749999999999999  0.8750000000000000  0.3750000000000000
 Li   0.3749999999999998  0.3749999999999999  0.8749999999999999
 Li   0.8749999999999998  0.3749999999999999  0.8750000000000000
 Li   0.3749999999999998  0.8750000000000000  0.8750000000000000
 Li   0.8749999999999998  0.8749999999999999  0.8749999999999999
 Os   0.0000000000000000  0.0000000000000000  0.0000000000000000
 Os   0.5000000000000000 -0.0000000000000000 -0.0000000000000000
 Os  -0.0000000000000000  0.5000000000000000 -0.0000000000000000
 Os   0.5000000000000000  0.5000000000000000 -0.0000000000000000
 Os   0.9999999999999999  0.9999999999999999  0.4999999999999999
 Os   0.4999999999999999  0.9999999999999999  0.4999999999999999
 Os   0.9999999999999999  0.4999999999999999  0.4999999999999999
 Os   0.4999999999999999  0.5000000000000000  0.5000000000000000
 Os   0.2499999999999999  0.2500000000000000  0.2500000000000000
 Os   0.7499999999999999  0.2500000000000000  0.2500000000000000
 Os   0.2499999999999999  0.7500000000000000  0.2500000000000000
 Os   0.7500000000000000  0.7500000000000000  0.2500000000000000
 Os   0.2499999999999998  0.2499999999999999  0.7499999999999999
 Os   0.7499999999999999  0.2499999999999999  0.7500000000000000
 Os   0.2499999999999998  0.7500000000000000  0.7499999999999999
 Os   0.7499999999999999  0.7500000000000000  0.7500000000000000
  O   0.3117142295000000  0.4382857705000000  0.1250000000000000
  O   0.8117142294999999  0.4382857705000000  0.1250000000000000
  O   0.3117142295000000  0.9382857705000002  0.1250000000000000
  O   0.8117142294999999  0.9382857705000001  0.1250000000000000
  O   0.3117142294999999  0.4382857704999999  0.6250000000000000
  O   0.8117142294999998  0.4382857704999999  0.6250000000000000
  O   0.3117142294999999  0.9382857705000001  0.6250000000000000
  O   0.8117142294999999  0.9382857705000001  0.6250000000000001
  O   0.1882857704999999  0.0617142295000000  0.3749999999999999
  O   0.6882857704999999  0.0617142294999999  0.3750000000000000
  O   0.1882857704999999  0.5617142295000001  0.3750000000000000
  O   0.6882857704999999  0.5617142295000001  0.3750000000000000
  O   0.1882857704999999  0.0617142294999999  0.8749999999999999
  O   0.6882857704999998  0.0617142294999999  0.8749999999999999
  O   0.1882857704999998  0.5617142294999999  0.8749999999999999
  O   0.6882857704999998  0.5617142294999999  0.8749999999999999
  O   0.4382857704999999  0.1250000000000000  0.3117142294999999
  O   0.9382857704999999  0.1250000000000000  0.3117142294999999
  O   0.4382857704999999  0.6250000000000000  0.3117142294999999
  O   0.9382857705000001  0.6250000000000000  0.3117142295000000
  O   0.4382857704999998  0.1249999999999999  0.8117142294999998
  O   0.9382857704999998  0.1249999999999999  0.8117142294999998
  O   0.4382857704999998  0.6249999999999999  0.8117142294999998
  O   0.9382857704999999  0.6250000000000000  0.8117142294999999
  O   0.0617142295000000  0.3750000000000000  0.1882857705000000
  O   0.5617142294999999  0.3750000000000000  0.1882857705000000
  O   0.0617142295000000  0.8750000000000000  0.1882857705000000
  O   0.5617142294999999  0.8750000000000000  0.1882857704999999
  O   0.0617142294999998  0.3749999999999999  0.6882857704999999
  O   0.5617142294999999  0.3750000000000000  0.6882857705000001
  O   0.0617142294999998  0.8750000000000000  0.6882857705000001
  O   0.5617142294999998  0.8749999999999999  0.6882857704999999
  O   0.1249999999999999  0.3117142295000000  0.4382857705000000
  O   0.6249999999999999  0.3117142294999999  0.4382857705000000
  O   0.1249999999999999  0.8117142294999998  0.4382857705000001
  O   0.6249999999999999  0.8117142294999999  0.4382857704999999
  O   0.1249999999999998  0.3117142294999999  0.9382857704999999
  O   0.6249999999999998  0.3117142294999999  0.9382857704999999
  O   0.1249999999999998  0.8117142294999998  0.9382857704999999
  O   0.6249999999999998  0.8117142294999998  0.9382857704999999
  O   0.3750000000000000  0.1882857705000000  0.0617142295000000
  O   0.8750000000000000  0.1882857705000000  0.0617142295000001
  O   0.3750000000000000  0.6882857705000001  0.0617142295000000
  O   0.8750000000000000  0.6882857705000002  0.0617142295000001
  O   0.3749999999999999  0.1882857705000000  0.5617142295000001
  O   0.8749999999999999  0.1882857704999999  0.5617142295000001
  O   0.3749999999999999  0.6882857705000001  0.5617142295000001
  O   0.8749999999999999  0.6882857704999999  0.5617142294999999
========================================================
Would someone give me some suggestions?

Thanks in advance.

Best,
Fermin
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