[Pw_forum] (no subject)

[Wang Di]

Dear All:
      I plan to calculate the phonon of the crystal structure with hexagonal
lattice. It spend me one day  to build the crystal structure which was
confirmed by Xcrysden. According the experiences of previous e-mails about
phonon calculate, the "relax " process of the crystal structure was needed,
then I  vc-relaxed the crystal structure and hoped to get a  approving
structure in a few hours. But the calculation had took more than 40
thousands second after 14 steps and stopped with the error : too many C-
bond were not converged.

input file:
&CONTROL
                 calculation = 'vc-relax' ,
                      outdir = '/root/espresso-4.2/work/Dean/LSAFB/temp/' ,
                      wfcdir = '/root/espresso-4.2/work/Dean/LSAFB/wftemp/'
,
                  pseudo_dir = '/root/espresso-4.2/work/Dean/LSAFB/pp/' ,
                      prefix = 'LSAF' ,
                 lkpoint_dir = .true. ,
               etot_conv_thr = 1.0D-5 ,
               forc_conv_thr = 1.0D-4 ,
                       nstep = 100 ,
                     tstress = .true. ,
                     tprnfor = .true. ,
                          dt = 20 ,
                    dipfield = .true. ,
 /
 &SYSTEM
                       ibrav = 4,
                   celldm(1) = 5.0716,
                   celldm(3) = 2.0093,
                         nat = 18,
                        ntyp = 4,
                     ecutwfc = 80 ,
                 occupations = 'smearing' ,
                     degauss = 0.02 ,
                    smearing = 'gaussian' ,
 /
 &ELECTRONS
            electron_maxstep = 100,
                    conv_thr = 1.0D-12 ,
                 mixing_mode = 'plain' ,
                 mixing_beta = 0.7D ,
 /
 &IONS
                ion_dynamics = 'bfgs' ,
           pot_extrapolation = 'second_order' ,
           wfc_extrapolation = 'second_order' ,
                     upscale = 10D ,
                   bfgs_ndim = 1 ,
            trust_radius_max = 0.8D0 ,
            trust_radius_min = 1.0D-3 ,
            trust_radius_ini = 0.5D ,
 /
ATOMIC_SPECIES
   Li    6.94100  Li.pbe-n-van.UPF
   Al   26.98154  Al.pbe-sp-van.UPF
   Sr   87.62000  Sr.pbe-nsp-van.UPF
    F   18.99840  F.pbe-n-van.UPF
ATOMIC_POSITIONS alat
   Sr      0.000000000    0.000000000    0.000000000
   Sr      0.000000000    0.000000000    1.004630000
   Li      0.500000000    0.288650000    1.500000000
   Li      0.000000000    0.577370000    0.502310000
   Al      0.500500000    0.288650000    0.502320000
   Al      0.000000000    0.577380000    1.506900000
    F      0.371500000    0.028400000    0.298380000
    F      0.789650000    0.307530000    0.298380000
    F      0.338850000    0.530090000    0.298380000
    F      0.661150000    0.530090000    0.706260000
    F      0.628500000    0.028400000    0.706260000
    F      0.210350000    0.307530000    0.706260000
    F      0.128500000    0.837620000    1.710890000
    F     -0.289650000    0.558500000    1.710890000
    F      0.161150000    0.335930000    1.710890100
    F     -0.161150000    0.335930000    1.303010000
    F     -0.128500000    0.837620000    1.303010000
    F      0.289650000    0.558500000    1.303010000
K_POINTS automatic
  8 8 8   1 1 1

I appreciate if one give me some advises to resolve the problem and the
reason.

Best regards

Wang Di
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