<div dir="ltr">Dear all,<div><br></div><div>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</div><div>==== vcrelax.out ===========</div><div><div>CELL_PARAMETERS (alat= 10.03700000)</div><div>   0.483245254  -0.279001778   0.825350540</div><div>   0.000000000   0.558003555   0.825350540</div><div>  -0.483245254  -0.279001778   0.825350540</div><div><br></div><div>ATOMIC_POSITIONS (crystal)</div><div>Li       0.250000000   0.250000000   0.250000000</div><div>Li       0.750000000   0.750000000   0.750000000</div><div>Os       0.000000000   0.000000000   0.000000000</div><div>Os       0.500000000   0.500000000   0.500000000</div><div>O        0.623428459   0.876571541   0.250000000</div><div>O        0.376571541   0.123428459   0.750000000</div><div>O        0.876571541   0.250000000   0.623428459</div><div>O        0.123428459   0.750000000   0.376571541</div><div>O        0.250000000   0.623428459   0.876571541</div><div>O        0.750000000   0.376571541   0.123428459</div><div>End final coordinates</div></div><div>=============================</div><div>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</div><div>===== <a href="http://001.in">001.in</a> ==================</div><div>  &control</div><div>    calculation='scf', </div><div>    restart_mode='from_scratch', </div><div>    prefix='001', </div><div>    outdir = './tmp/', </div><div>    pseudo_dir = '/home/QE/espresso-5.1.2/pslibrary.1.0.0/pbe/PSEUDOPOTENTIALS/',</div><div>    max_seconds = 172000</div><div>    wf_collect = .false.</div><div> /</div><div> &system    </div><div>    nat = 80</div><div>    ntyp = 3</div><div>    ibrav = 0</div><div>    ecutwfc =60 </div><div>    ecutrho=480</div><div> /</div><div> &electrons</div><div>   mixing_beta=0.3D0,</div><div>    conv_thr=1.D-8</div><div>    electron_maxstep=200</div><div> /</div><div> &ions</div><div> /</div><div>&cell</div><div> /</div><div>K_POINTS AUTOMATIC</div><div>4 4 4 0 0 0</div><div>CELL_PARAMETERS bohr</div><div>    9.7006599999999992   -5.6006799999999997   16.5680799999999984</div><div>    0.0000000000000000   11.2013599999999993   16.5680799999999984</div><div>   -9.7006599999999992   -5.6006799999999997   16.5680799999999984</div><div>ATOMIC_SPECIES</div><div> Li    6.94100   Li.pbe-s-rrkjus_psl.1.0.0.UPF</div><div> Os  190.23000   Os.pbe-spn-rrkjus_psl.1.0.0.UPF</div><div>  O   15.99940   O.pbe-n-rrkjus_psl.1.0.0.UPF</div><div>ATOMIC_POSITIONS crystal</div><div> Li   0.1260000353821472  0.1250000000000000  0.1250000000000000</div><div> Li   0.6249999999999999  0.1250000000000000  0.1250000000000000</div><div> Li   0.1250000000000000  0.6250000000000000  0.1250000000000000</div><div> Li   0.6250000000000000  0.6250000000000000  0.1250000000000000</div><div> Li   0.1249999999999999  0.1249999999999999  0.6250000000000000</div><div> Li   0.6249999999999999  0.1249999999999999  0.6250000000000000</div><div> Li   0.1249999999999999  0.6249999999999999  0.6250000000000000</div><div> Li   0.6249999999999998  0.6249999999999999  0.6249999999999999</div><div> Li   0.3749999999999999  0.3750000000000000  0.3750000000000000</div><div> Li   0.8749999999999999  0.3749999999999999  0.3750000000000000</div><div> Li   0.3749999999999999  0.8750000000000000  0.3749999999999999</div><div> Li   0.8749999999999999  0.8750000000000000  0.3750000000000000</div><div> Li   0.3749999999999998  0.3749999999999999  0.8749999999999999</div><div> Li   0.8749999999999998  0.3749999999999999  0.8750000000000000</div><div> Li   0.3749999999999998  0.8750000000000000  0.8750000000000000</div><div> Li   0.8749999999999998  0.8749999999999999  0.8749999999999999</div><div> Os   0.0000000000000000  0.0000000000000000  0.0000000000000000</div><div> Os   0.5000000000000000 -0.0000000000000000 -0.0000000000000000</div><div> Os  -0.0000000000000000  0.5000000000000000 -0.0000000000000000</div><div> Os   0.5000000000000000  0.5000000000000000 -0.0000000000000000</div><div> Os   0.9999999999999999  0.9999999999999999  0.4999999999999999</div><div> Os   0.4999999999999999  0.9999999999999999  0.4999999999999999</div><div> Os   0.9999999999999999  0.4999999999999999  0.4999999999999999</div><div> Os   0.4999999999999999  0.5000000000000000  0.5000000000000000</div><div> Os   0.2499999999999999  0.2500000000000000  0.2500000000000000</div><div> Os   0.7499999999999999  0.2500000000000000  0.2500000000000000</div><div> Os   0.2499999999999999  0.7500000000000000  0.2500000000000000</div><div> Os   0.7500000000000000  0.7500000000000000  0.2500000000000000</div><div> Os   0.2499999999999998  0.2499999999999999  0.7499999999999999</div><div> Os   0.7499999999999999  0.2499999999999999  0.7500000000000000</div><div> Os   0.2499999999999998  0.7500000000000000  0.7499999999999999</div><div> Os   0.7499999999999999  0.7500000000000000  0.7500000000000000</div><div>  O   0.3117142295000000  0.4382857705000000  0.1250000000000000</div><div>  O   0.8117142294999999  0.4382857705000000  0.1250000000000000</div><div>  O   0.3117142295000000  0.9382857705000002  0.1250000000000000</div><div>  O   0.8117142294999999  0.9382857705000001  0.1250000000000000</div><div>  O   0.3117142294999999  0.4382857704999999  0.6250000000000000</div><div>  O   0.8117142294999998  0.4382857704999999  0.6250000000000000</div><div>  O   0.3117142294999999  0.9382857705000001  0.6250000000000000</div><div>  O   0.8117142294999999  0.9382857705000001  0.6250000000000001</div><div>  O   0.1882857704999999  0.0617142295000000  0.3749999999999999</div><div>  O   0.6882857704999999  0.0617142294999999  0.3750000000000000</div><div>  O   0.1882857704999999  0.5617142295000001  0.3750000000000000</div><div>  O   0.6882857704999999  0.5617142295000001  0.3750000000000000</div><div>  O   0.1882857704999999  0.0617142294999999  0.8749999999999999</div><div>  O   0.6882857704999998  0.0617142294999999  0.8749999999999999</div><div>  O   0.1882857704999998  0.5617142294999999  0.8749999999999999</div><div>  O   0.6882857704999998  0.5617142294999999  0.8749999999999999</div><div>  O   0.4382857704999999  0.1250000000000000  0.3117142294999999</div><div>  O   0.9382857704999999  0.1250000000000000  0.3117142294999999</div><div>  O   0.4382857704999999  0.6250000000000000  0.3117142294999999</div><div>  O   0.9382857705000001  0.6250000000000000  0.3117142295000000</div><div>  O   0.4382857704999998  0.1249999999999999  0.8117142294999998</div><div>  O   0.9382857704999998  0.1249999999999999  0.8117142294999998</div><div>  O   0.4382857704999998  0.6249999999999999  0.8117142294999998</div><div>  O   0.9382857704999999  0.6250000000000000  0.8117142294999999</div><div>  O   0.0617142295000000  0.3750000000000000  0.1882857705000000</div><div>  O   0.5617142294999999  0.3750000000000000  0.1882857705000000</div><div>  O   0.0617142295000000  0.8750000000000000  0.1882857705000000</div><div>  O   0.5617142294999999  0.8750000000000000  0.1882857704999999</div><div>  O   0.0617142294999998  0.3749999999999999  0.6882857704999999</div><div>  O   0.5617142294999999  0.3750000000000000  0.6882857705000001</div><div>  O   0.0617142294999998  0.8750000000000000  0.6882857705000001</div><div>  O   0.5617142294999998  0.8749999999999999  0.6882857704999999</div><div>  O   0.1249999999999999  0.3117142295000000  0.4382857705000000</div><div>  O   0.6249999999999999  0.3117142294999999  0.4382857705000000</div><div>  O   0.1249999999999999  0.8117142294999998  0.4382857705000001</div><div>  O   0.6249999999999999  0.8117142294999999  0.4382857704999999</div><div>  O   0.1249999999999998  0.3117142294999999  0.9382857704999999</div><div>  O   0.6249999999999998  0.3117142294999999  0.9382857704999999</div><div>  O   0.1249999999999998  0.8117142294999998  0.9382857704999999</div><div>  O   0.6249999999999998  0.8117142294999998  0.9382857704999999</div><div>  O   0.3750000000000000  0.1882857705000000  0.0617142295000000</div><div>  O   0.8750000000000000  0.1882857705000000  0.0617142295000001</div><div>  O   0.3750000000000000  0.6882857705000001  0.0617142295000000</div><div>  O   0.8750000000000000  0.6882857705000002  0.0617142295000001</div><div>  O   0.3749999999999999  0.1882857705000000  0.5617142295000001</div><div>  O   0.8749999999999999  0.1882857704999999  0.5617142295000001</div><div>  O   0.3749999999999999  0.6882857705000001  0.5617142295000001</div><div>  O   0.8749999999999999  0.6882857704999999  0.5617142294999999</div><div>========================================================</div><div>Would someone give me some suggestions? </div><div><br></div><div>Thanks in advance.</div><div><br></div><div>Best,</div><div>Fermin</div></div>