[QE-users] cp.x diverges with multiple thermostats

[Merlin Meheut]

Dear PWSCF users,

I am trying to realize a cp dynamics of a Ca2+ + 2Cl- + 64 H2O solution,
and I successfully realized NVE dynamics, and NVT dynamics with a single
thermostat ( nhpcl  = 1,   nhptyp = 0,). However, when I try with more
thermostats (nhpcl>1 and/or nhptyp>0), the energy systematically  diverges.
More precisely, the quantity called "vnhp" is the first to diverge and the
one showing the more obvious divergency. Would you have any hints on what
to do? I would be very grateful if you could guide me on which parameters
may have the most effect on this divergency?

Below is a typical input of this divergent computation

 &control
       calculation = 'cp',
      restart_mode = 'reset_counters',
            prefix = 'CaCl2-62wrl',
           disk_io = 'default' ,
    pseudo_dir     = '$WORKDIR',
    outdir         = '${WORKDIR}',
    tprnfor        = .true.,
    tstress        = .true.,
    dt             =  5.0,
    ndr=53,
    ndw = 54,
    nstep          =  30000,
    iprint         =  30,
    isave          =  30,
    etot_conv_thr = 1.d-4,
    ekin_conv_thr = 1.d-4,
    forc_conv_thr = 1.d-3,
/&end
 &system
    ibrav = 0, celldm(1)=23.4752,
    nat = 189, ntyp = 4, ecutwfc = 80.0, ecutrho=320.0,
    nr1b=20, nr2b=20,nr3b=20,
/&end
 &electrons
    emass = 400.d0,
    emass_cutoff = 2.5d0,
    orthogonalization = 'ortho',
    ortho_eps = 5.d-8,
    ortho_max = 25,
    electron_dynamics = 'verlet', ! 'damp', !'verlet',
    electron_velocities='default',
    electron_temperature='not_controlled',
 /
 &ions
    ion_dynamics = 'verlet',
    ion_radius(1) = 1.0d0,
    ion_radius(2) = 1.0d0,
    ion_radius(3) = 0.8d0,
    ion_radius(4) = 0.5d0,
    ion_velocities = 'default',
    ion_temperature = 'nose',
    tempw=300.0,
    fnosep =  60.0,
    nhpcl  = 2,
    nhptyp = 1,
 /
 &cell
    cell_dynamics = 'none',
    cell_velocities = 'zero',
    press = 0.0d0,
    wmass = 70000.0d0
 /
ATOMIC_SPECIES
  Ca   39.9625   Ca.blyp-spn-rrkjus_psl.1.0.0.UPF
  Cl   34.9689   Cl.blyp-nl-rrkjus_psl.1.0.0.UPF
  O    15.9949   O.blyp.UPF
  H     1.0079   H.blyp2.UPF

CELL_PARAMETERS (alat= 23.47520000)
   1.000000000   0.000000000   0.000000000
   0.000000000   1.000000000   0.000000000
   0.000000000   0.000000000   1.000000000

ATOMIC_POSITIONS (bohr)
(...)

Thanks in advance,

-- 
Merlin Méheut
adresse labo:
GET - OMP   - Université Paul Sabatier
14 avenue Edouard Belin
31400 Toulouse
FRANCE
tel: (+33) 5 61 33 26 17
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