[QE-users] CPMD Electron Relaxation takes too long.
Giuliana Materzanini
giuliana.materzanini at epfl.ch
Fri Jan 11 07:52:28 CET 2019
Dear Oier,
here are my comments/advices:
(*) I would recommend stricter convergence criteria: ekin_conv_thr =
1.0d-11 (or 1.0d-9 at least), etot_conv_thr = 1.0d-6.
(**) dt is not the only parameter to set in CP: you should tune emass
and emass_cutoff, for which you are now using the default values. Beside
choosing a lower value of dt, also choosing a lower value of
emass_cutoff should help you to avoid that "ortho goes bananas". In any
case, you solved this. But remember that tuning these three parameters,
emass, emass_cutoff and dt, will be crucial for your MD simulation (you
should tune them in such a way that ekin_electrons is much lower than
ekin_ions and that econt is conserved - see file .evp for these quantities).
(***) for electron_dynamics, why don't you use damped dynamics? Put
electron_dynamics='damp', electron_damping=0.2, and if needed tune
electron_damping (see the user's guide). In my experience damped
dynamics is faster than sd, and this could be the reason why you are stuck.
(****) Just to clarify: step 1) is reaching the GS, that means relaxing
the electrons; step 2) is relaxing the system, i.e. relaxing the ions.
Hope this helps!
Best regards,
Giuliana
--
****************************************************
Giuliana Materzanini
Theory and Simulation of Materials
École Polytechnique Fédérale de Lausanne
****************************************************
On 10/01/19 17:29, Oier Arcelus wrote:
> 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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