[QE-users] vc-cp

[Mohammad Moaddeli]

Dear all,

I am trying to relax a large structure (about 100 atoms) containing organic
molecules. Since vc-relax using the BFGS algorithm takes a long time to
converge, I want to relax the structure using the Car-Parrinello method
(QE_6.7). I am wondering if the following procedure is correct:

*1) electron relaxation:*
&control
    calculation = 'cp'
    restart_mode = 'from_scratch'
    nstep=10000, iprint=10, isave=100,
    etot_conv_thr=1.d-7,
    ekin_conv_thr=1.d-7,
    dt=1.0,
    ndr=50, ndw=50,
/
&system
    ecutwfc = 40, ecutrho = 300,
    nr1b=20, nr2b=20, nr3b=20,
/
&electrons
    electron_dynamics='damp', electron_damping=0.05,
    emass=300,
    orthogonalization='ortho', ortho_eps=1.d-11, ortho_max=200,
    conv_thr = 1.0D-6,
/
&ions
    ion_dynamics = 'none'
/
&cell
    cell_dynamics = 'none'
/
......................................................

*2) random displacement:*
&control
    calculation = 'cp'
    restart_mode = 'restart'
    nstep=10000, iprint=10, isave=100,
    etot_conv_thr=1.d-7,
    ekin_conv_thr=1.d-7,
    dt=1.0,
    ndr=50, ndw=51,
/
&system
    ecutwfc = 40, ecutrho = 300,
    nr1b=20, nr2b=20, nr3b=20,
/
&electrons
    electron_dynamics='damp', electron_damping=0.05,
    emass=300,
    orthogonalization='ortho', ortho_eps=1.d-11, ortho_max=200,
    conv_thr = 1.0D-6,
/
&ions
    ion_dynamics = 'none'
    tranp = .true.
    amprp = 0.03,
/
&cell
    cell_dynamics = 'none'
/
......................................................

*3) running vc-cp including ion_dinamics and cell_dynamics:*
&control
    calculation = 'vc-cp'
    restart_mode = 'reset_counters'
    nstep=500000, iprint=10, isave=100,
    etot_conv_thr=1.d-7,
    ekin_conv_thr=1.d-7,
    dt=5.0,
    ndr=51, ndw=52,
/
&system
    ecutwfc = 30, ecutrho = 200,
    nr1b=20, nr2b=20, nr3b=20,
/
&electrons
    electron_dynamics = 'verlet'
    emass=700,
    orthogonalization='ortho',
    conv_thr = 1.0D-6,
/
&ions
    ion_dynamics = 'verlet'
    ion_velocities = 'zero'
/
&cell
    cell_dynamics = 'damp-pr'
    cell_dofree = 'xyz'
/

I ran three inputs based on the above steps, but the kinetic energy is
rising. I ran an scf using pw.x with the positions/cell_parameters at 0th,
1000th, 2000th and ... NFIs, but total_energy and total_force is rising.

Any help will be greatly appreciated.

Best regards,

Mohammad Moaddeli
ShirazU
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