[QE-users] CPMD Electron Relaxation takes too long.

[Oier Arcelus]

Dear All,

I am trying to run the cp.x to analyze Na ion dynamics into a rigid layered host structure. The first test is to try to run the simulation on a small unit cell of layered NaFeO2. As I read in the user guide https://www.quantum-espresso.org/Doc/cp_user_guide/ there are few steps. 1) Reach the GS 2) Relax the electrons 3) Run the dynamics. For the first step I am using the following input file:
User's Guide for The Quantum ESPRESSO Car-Parrinello Molecular Dynamics<https://www.quantum-espresso.org/Doc/cp_user_guide/>
Pietro Delugas 2018-03-16
www.quantum-espresso.org

 &control
   calculation='cp'
   restart_mode='from_scratch',
   iprint = 10
   isave = 100
   ndr = 51
   ndw = 51
   nstep = 100
   tstress = .TRUE.
   tprnfor = .TRUE.
   dt = 2.5d0
   etot_conv_thr = 1.0d-5
   ekin_conv_thr = 1.0d-4
   pseudo_dir='/home/enxararo/NaFeO2/pseudos/',
   outdir='./'
   prefix='nafeo'
 /
 &system
   ibrav = 0
   nat= 12
   ntyp= 3
   ecutwfc = 90
   ecutrho = 900
   nr1b = 20, nr2b = 20, nr3b = 65
   nspin = 2
   tot_magnetization = 5.0
   lda_plus_u = .TRUE.
   Hubbard_U(2) = 3.9
   vdw_corr = TS
 /
 &electrons
   electron_dynamics = 'sd'
 /
 &ions
   ion_dynamics = 'none'
 /
 &cell
   cell_dynamics = 'none'
   press = 0.0d0
 /
 ATOMIC_SPECIES
 Na 51 Na.pbe-spnl-rrkjus_psl.1.0.0.UPF
 Fe 72 Fe.pbe-n-rrkjus_psl.1.0.0.UPF
 O 16.0 O.pbe-n-rrkjus_psl.1.0.0.UPF
 ATOMIC_POSITIONS (crystal)
  Na   0.333332980         0.666666973         0.166666995
  Na   0.000000000         0.000000000         0.500000000
  Na   0.666666991         0.333332969         0.833333020
  Fe   0.000000000         0.000000000         0.000000000
  Fe   0.666666991         0.333332969         0.333332991
  Fe   0.333332980         0.666666973         0.666666980
  O   0.666666991         0.333332969         0.067304000
  O   0.000000000         0.000000000         0.266029012
  O   0.333332980         0.666666973         0.400636998
  O   0.666666991         0.333332969         0.599363031
  O   0.000000000         0.000000000         0.733970988
  O   0.333332980         0.666666973         0.932695992
 CELL_PARAMETERS {angstrom}
        3.0578720570         0.0000000000         0.0000000000
       -1.5289360285         2.6481948829         0.0000000000
        0.0000000000         0.0000000000        16.2363090515

I've noticed a few things.
1) Trying to use the estimation of nr1b, nr2b, and nr3b that appears in the user guide point 4.4.4 resulted in a SIGSEV:segmentation fault. Reducing it to the values of the input I attached solved the problem.
2) Using a value of dt = 5.0 resulted in an error from routine 'ortho: orthogonalization went bananas' or something like that. Setting it to dt = 2.5 gets rid of this problem.
3) Last, and most importantly, I've been running this 12 atom system for about 6 hours now and it is stuck on the following:

.
.
.
   Wave Initialization: random initial wave-functions
   Occupation number from init
   spin =   1 nbnd =    46
    1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00
    1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00
    1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00
    1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00
    1.00 1.00 1.00 1.00 1.00 1.00
   spin =   2 nbnd =    41
    1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00
    1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00
    1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00
    1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00
    1.00

   formf: eself=   519.42285
   formf:     vps(g=0)=  -0.0016489     rhops(g=0)=  -0.0091918
   formf: sum_g vps(g)=  -0.7698402 sum_g rhops(g)=  -6.4702082
   formf:     vps(g=0)=   0.0136252     rhops(g=0)=  -0.0081705
   formf: sum_g vps(g)=   4.1620329 sum_g rhops(g)=  -5.7512961
   formf:     vps(g=0)=  -0.0001694     rhops(g=0)=  -0.0061279
   formf: sum_g vps(g)=   0.3628532 sum_g rhops(g)=  -4.3134721
   Delta V(G=0):   0.077012Ry,    2.095591eV

   from rhoofr: total integrated electronic density
   spin up
   in g-space =     46.000000   in r-space =    46.000000
   spin down
   in g-space =     41.000000   in r-space =    41.000000

     TS-vdW Pressure (GPa)        2.30153      0
     Total Electronic Pressure (GPa)     7162.86920      0

Is this normal? The scf calculations with pw.x does not take more than a minute to solve this system. Any help is very much appreciated!

Thanks in advance,

Best regards,

Oier.
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