[Pw_forum] cpmd cannot reach the electronic ground state

[DONG Juncai]

Dear all,
 
I have carried out cpmd calculation with cp.x on a Ge diamond-structured 2x1x1 supercell. However, it seems like that it is impossible to reach the electronic ground state. It is weird that the Scf total energy is positive and much large as listed following. 
  nfi    ekinc  temph  tempp           etot         enthal          econs          econt    vnhh   xnhh0    vnhp   xnhp0
    1 ********    0.0    0.0    17152.83801    17152.83801    17152.83801    29797.11310  0.0000  0.0000  0.0000  0.0000
    2 ********    0.0    0.0     7970.13546     7970.13546     7970.13546    34498.19739  0.0000  0.0000  0.0000  0.0000
    3 ********    0.0    0.0    28546.42723    28546.42723    28546.42723    58500.61459  0.0000  0.0000  0.0000  0.0000
    4 ********    0.0    0.0    95316.89267    95316.89267    95316.89267   128235.67301  0.0000  0.0000  0.0000  0.0000
    5 ********    0.0    0.0    68985.53624    68985.53624    68985.

I have tried to tune emass, dt, cut-offs, however, it doesn't work. 

I use the pp Ge.pbe-dn-rrkjus_psl.0.2.2.UPF from http://www.quantum-espesso.org

Any idea about what might be causing this problem? My input file is appended.

 &CONTROL
    title = 'cd_211 ',
    calculation='cp',
    restart_mode='from_scratch',
    ndr = 51,
    ndw = 51,
    nstep=500,
    iprint = 10,
    isave  = 1000,
    tstress = .TRUE.,
    tprnfor = .TRUE.,
    dt = 3.0d0,
    etot_conv_thr = 1.d-9,
    ! forc_conv_thr = 1.d-3
    ekin_conv_thr = 1.d-4,
    prefix = 'bct_Ge'
    pseudo_dir = '/home/Ge/cpmd/',
    outdir='/home/Ge/cpmd/',
    ! disk_io='high'
 /
 &SYSTEM
    ibrav = 14,
    celldm(1) = 21.382,
    celldm(2)= 0.5,
    celldm(3)= 0.5,
    celldm(4)=0,
    celldm(5)=0,
    celldm(6)=0,
    nat=  16, ntyp= 1,
    ecutwfc = 40.0,
    ecutrho = 400.0,
    nr1b = 15, nr2b = 15, nr3b = 15,
 /
 &ELECTRONS
    emass = 300.d0,
    emass_cutoff = 2.5d0,
    orthogonalization = 'Gram-Schmidt',
    electron_dynamics = 'sd',
    conv_thr =  1.0d-6,
    ! electron_damping = 0.2,
    electron_velocities = 'zero',
 /
 &IONS
    ion_dynamics = 'none',
    ! ion_velocities = 'zero',
    ! ion_damping = 0.1,
 /
ATOMIC_SPECIES
 Ge  72.64 Ge.pbe-dn-rrkjus_psl.0.2.2.UPF
ATOMIC_POSITIONS crystal
 Ge   -0.00000   0.00000   0.00000
 Ge   -0.00000   0.50000   0.50000
 Ge    0.25000   0.00000   0.50000
 Ge    0.25000   0.50000   0.00000
 Ge    0.37500   0.25000   0.75000
 Ge    0.12500   0.25000   0.25000
 Ge    0.12500   0.75000   0.75000
 Ge    0.37500   0.75000   0.25000
 Ge    0.50000   0.00000   0.00000
 Ge    0.50000   0.50000   0.50000
 Ge    0.75000   0.00000   0.50000
 Ge    0.75000   0.50000   0.00000
 Ge    0.87500   0.25000   0.75000
 Ge    0.62500   0.25000   0.25000
 Ge    0.62500   0.75000   0.75000
 Ge    0.87500   0.75000   0.25000


Thanks,
Dong

--
Juncai Dong
PhD. Candidate
Beijing Synchrotron Radiation Facility (BSRF)
Institute of High Energy Physics
Chinese Academy of Sciences
P.R.China