[Pw_forum] Iron surface Molecular Dynamics

[Giuseppe Mattioli]

Dear Vincenzo
Before discussing your setup, I note that you are using the ensemble-DFT approach implemented in cp.x. I suspect (but perhaps I may be wrong), that it 
cannot be used to propagate ions in a proper (NVT, NPT, ...) molecular dynamics simulation, but only to optimize structures through damped molecular 
dynamics. Have you tried first to optimize your system by using pw.x instead of cp.x, and some smearing scheme to deal with metallic systems? You could 
eventually consider (especially if there are no H atoms involved) a Born-Oppenheimer MD with pw.x as a good solution...
HTH
Giuseppe

On Wednesday 08 May 2013 16:00:01 Vincenzo Verdolino wrote:
> Dear all,
> 
> I am dealing with Iron surface catalyst and I'm trying to run MD simulation
> with cp.x
> 
> Here is My Input file
> 
>  &control
>     pseudo_dir = '/cluster/home/chab/verdoliv/espresso/pseudo/',
>     outdir='/cluster/work/scr1/verdoliv/Initial_wavefunction_min/output'
>     prefix='Initial_wavefunction_min',
>     title=Initial_wavefunction_min,
>     calculation='cp',
>     restart_mode = 'from_scratch',
>     nstep  = 50,
>     iprint = 10,
>     isave  = 100,
>     tstress = .FALSE.,
>     tprnfor = .TRUE.,
>     dt    = 4.0d0,
>     etot_conv_thr = 1.d-9,
>     ekin_conv_thr = 1.d-4,
>     ndr = 50
>     ndw = 51,
>  /
>  &system
>     ibrav=  8,
>     C=38.9305, A=7.02146, B=8.10768, cosAB=0.0, cosAC=0.0, cosBC=0.0,
>     nat= 50,
>     ntyp= 2,
>     ecutwfc = 80.0, ecutrho = 640.0,
>     smearing='cs',
>     occupations='ensemble',
>     nbnd = 550,
>     nspin=1,
>     nr1b=24, nr2b=24, nr3b=24,
>  /
>  &electrons
>              orthogonalization = 'ortho',
>              startingwfc = 'random',
>              electron_dynamics = 'sd',
>              ampre = 0.02,
>              tcg = .true.,
>              passop= 0.3,
>              maxiter = 250,
>              emass = 300,
>              emass_cutoff = 3.00,
>              conv_thr=1.d-6
>              n_inner = 2,
>              lambda_cold = 0.03,
>              niter_cold_restart = 2,
>  /
>  &IONS
>   ion_dynamics = 'none',
>   ion_temperature = 'not_controlled',
>  /
> ATOMIC_SPECIES
> ATOMIC_SPECIES
>  Fe  1.  Fe.pw91-sp-van_ak.UPF
>  N   1.  N.pw91-van_ak.UPF
> ATOMIC_POSITIONS angstrom
> Fe      3.517670906   2.029585846   0.473063369
> Fe      3.517670906   6.078055744   0.473063369
> Fe      0.010178272   0.000000000   0.479139716
> Fe      0.010074125   4.053800000   0.476810499
> Fe      4.689525652   0.000000000   1.143911287
> Fe      4.690724988   4.053800000   1.146913875
> Fe      1.178101394   2.026148930   1.147504081
> Fe      1.178101394   6.081492660   1.147504081
> ...
> ...
> N        2.348065911   4.053800000  10.444508962
> N        2.349799703   4.053800000  11.564212110
> 
> ---------------------------------------------------------------------------
> -
> 
> The output file says
> 
> 
>  PERFORMING CONJUGATE GRADIENT MINIMIZATION OF EL. STATES
>  cg_sub: missed minimum, case 3, iteration           2
>  cg_sub: missed minimum, case 3, iteration           3
>  cg_sub: missed minimum, case 1, iteration           5
>  cg_sub: missed minimum, case 1, iteration           8
>  cg_sub: missed minimum, case 1, iteration          10
>  cg_sub: missed minimum, case 1, iteration          11
>  cg_sub: missed minimum, case 1, iteration          13
>  cg_sub: missed minimum, case 1, iteration          14
>  cg_sub: missed minimum, case 1, iteration          16
>  cg_sub: missed minimum, case 1, iteration          18
>  cg_sub: missed minimum, case 1, iteration          20
>  cg_sub: missed minimum, case 1, iteration          22
>  cg_sub: missed minimum, case 1, iteration          23
>  cg_sub: missed minimum, case 1, iteration          25
>  cg_sub: missed minimum, case 1, iteration          27
>  cg_sub: missed minimum, case 1, iteration          28
>  cg_sub: missed minimum, case 1, iteration          30
>  cg_sub: missed minimum, case 1, iteration          32
>  cg_sub: missed minimum, case 1, iteration          34
> 
> 
> Could any of you give my hints on this field?
> 
> Thanks in advance
> 
> Vincenzo


********************************************************
- Article premier - Les hommes naissent et demeurent
libres et ègaux en droits. Les distinctions sociales
ne peuvent être fondèes que sur l'utilitè commune
- Article 2 - Le but de toute association politique
est la conservation des droits naturels et 
imprescriptibles de l'homme. Ces droits sont la libertè,
la propriètè, la sùretè et la rèsistance à l'oppression.
********************************************************

   Giuseppe Mattioli                            
   CNR - ISTITUTO DI STRUTTURA DELLA MATERIA   
   v. Salaria Km 29,300 - C.P. 10                
   I 00015 - Monterotondo Stazione (RM)          
   Tel + 39 06 90672836 - Fax +39 06 90672316    
   E-mail: <giuseppe.mattioli at ism.cnr.it>
   ResearcherID: F-6308-2012