The Driver object

The Driver object is a simple way to call the QE/QEpy from python side. Here is how to define a simple scf job:

from qepy import Driver
driver = Driver('qe_in.in')

Here, the first argument specifies the name of QE input file.

List of all Methods

class qepy.driver.Driver(inputfile=None, comm=None, ldescf=False, iterative=False, task='scf', embed=None, prefix=None, outdir=None, logfile=None, qe_options=None, prog='pw', **kwargs)

The driver of QEpy.

Parameters

• inputfile (str) -- Name of QE input file

• comm (object) -- Parallel communicator

• ldescf (bool) -- If True, also print the scf correction term in the iteratively mode

• iterative (bool) -- Iteratively run the scf or tddft

• task (str) --

  Task of the driver :

  • 'scf' : scf task

  • 'optical' : Optical absorption spectrum (TDDFT)

  • 'nscf' : read file from scf

• embed (object (Fortran)) -- embed object for QE

• prefix (str) -- prefix of QE input/output

• outdir (str) -- The output directory of QE

• logfile (str, file or bool) --

  The screen output of QE. If it is a file descriptor, it should open with 'w+'.

  • None : Show on the screen.

  • str : Save to the given file.

  • True : Save to the temporary file, see also qepy.driver.Driver.get_output().

• outdir -- The output directory of QE

• qe_options (dict) -- A dictionary with input parameters for QE to generate QE input file.

• kwargs (dict) -- Other options

Note

• The bool gather parameter in functions means the data is gathered in root or distributed in all cpus.

• Also contains some interface of ASE calculator, but the units are different.

  • positions : Bohr

  • lattice : Bohr

  • energy : Ry

  • forces : Ry/Bohr

  • stress : Ry/Bohr**3

  • potential : Ry

  • density : 1.0/Bohr**3

calc_energy(**kwargs)

Calculate the energy with the pw2casino of QE.

check_convergence(**kwargs)

Check the convergence of the SCF

data2field(data, cell=None, grid=None)

QE data to dftpy DirectField, please call it in serial.

diagonalize(print_level=2, **kwargs)

Diagonalize the hamiltonian

Parameters

print_level -- The level of output of QE

driver_initialize(**kwargs)

Initialize the driver

Parameters

• inputfile (str) -- Name of QE input file

• commf (object) -- Parallel communicator (Fortran)

• iterative (bool) -- Iteratively run the scf or tddft

• task (str) --

  Task of the driver :

  • 'scf' : scf task

  • 'optical' : Optical absorption spectrum (TDDFT)

  • 'nscf' : read file from scf

• qe_options (dict) -- A dictionary with input parameters for QE to generate QE input file.

end_scf(**kwargs)

End the scf and clean the scf workspace. Only need run it in iterative mode

field2data(field, data=None)

dftpy DirectField to QE data, please call it in serial.

classmethod get_ase_atoms()

Return the atom.Atoms from QE.

get_bz_k_points()

Return all the k-points in the 1. Brillouin zone.

The coordinates are relative to reciprocal latice vectors.

get_density(gather=True)

Return density array in real space.

classmethod get_dftpy_ions()

Return the dftpy.Ions from QE.

get_dipole_tddft()

Return the total dipole of tddft task.

get_effective_potential(spin=0, pad=True)

Return pseudo-effective-potential array.

get_eigenvalues(kpt=0, spin=0)

Return eigenvalue array.

get_energy(**kwargs)

Return the total energy.

get_fermi_level()

Return the Fermi level.

get_forces(icalc=0, **kwargs)

Return the total forces. (n, 3)

Parameters

icalc (int) --

icalc	without	bin
0	all	000
1	no ewald	001
2	no local	010
3	no ewald + local	011
4	no nlcc	100
5	no ewald + nlcc	101
6	no local + nlcc	110
7	no ewald + local + nlcc	111

get_ibz_k_points()

Return k-points in the irreducible part of the Brillouin zone.

The coordinates are relative to reciprocal latice vectors.

static get_ions_lattice()

Return the lattice of ions.

static get_ions_positions()

Return the cartesian positions of ions.

static get_ions_symbols()

Return the symbols of ions.

get_k_point_weights()

Weights of the k-points.

The sum of all weights is one.

get_magnetic_moment(**kwargs)

Return the total magnetic moment.

get_number_of_bands()

Return the number of bands.

get_number_of_grid_points(gather=True)

Return the shape of arrays.

get_number_of_k_points()

Return the number of kpoints.

get_number_of_spins()

Return the number of spins in the calculation.

Spin-paired calculations: 1, spin-polarized calculation: 2.

get_occupation_numbers(kpt=0, spin=0)

Return occupation number array.

get_output()

Return the output of QE.

It depends on the logfile of the initialization of the driver :

• None : return None.

• str : return all outputs.

• True : It will return the output from last time.

get_potential_energy(**kwargs)

Return the potential energy.

get_pseudo_density(spin=None, pad=True, gather=True)

Return pseudo-density array.

If spin is not given, then the total density is returned. Otherwise, the spin up or down density is returned (spin=0 or 1).

get_pseudo_wave_function(band=None, kpt=0, spin=0, broadcast=True, pad=True)

Return pseudo-wave-function array.

get_scf_error(**kwargs)

Return the error of the scf

get_scf_steps(**kwargs)

Return the number of steps of scf

get_spin_polarized()

Is it a spin-polarized calculation?

get_stress(**kwargs)

Return the stress (3, 3).

get_wave_function(band=None, kpt=0)

Return wave-function array in real space.

get_xc_functional()

Return the XC-functional identifier.

'LDA', 'PBE', ...

property is_root

Whether it is the root.

If the comm is set, root is rank == 0. Otherwise root is ionode of QE.

mix(mix_coef=0.7, print_level=2)

Mixing the density

Parameters

print_level -- The level of output of QE

pwscf_restart(oldxml=False)

Read PW ouput/restart files.

Parameters

oldxml (bool) --

• True : read the old format xml file (qe<6.4)

• False : read the new format xml file (qe>6.3)

save(what='all', **kwargs)

Save the QE data to the disk

Parameters

what (str) --

• what = 'all'write xml data file, charge density, wavefunctions

  (for final data);

• what = 'config'write xml data file and charge density; also,

  for nks=1, wavefunctions in plain binary format (see why in comments below). For intermediate or incomplete results;

• what = 'config-nowf'write xml data file and charge density only;

  (save density);

• what = 'config-init'write xml data file only excluding final results

  (for dry run, can be called at early stages).

see PW/src/punch.f90

scf(print_level=2, maxiter=None, **kwargs)

Run the scf/tddft until converged or maximum number of iterations

set_external_potential(potential, exttype=None, gather=True, extene=None, **kwargs)

Set the external potential.

Parameters

• potential ((nnr, nspin)) -- The external potential

• exttype (int) --

  The type of external potential

  type	potential	bin
  0	external	000
  1	pseudo	001
  2	hartree	010
  3	pseudo + hartree	011
  4	xc	100
  5	pseudo + xc	101
  6	hartree + xc	110
  7	pseudo + hartree + xc	111

stop(exit_status=0, what='all', print_flag=0, **kwargs)

stop.

Parameters

• exit_status (int) -- 0 : QE will remove it temporary files

• print_flag (int) -- 0 : Not print time informations

• what (str) -- see qepy.driver.Driver.save().

tddft_initialize(inputfile=None, commf=None, embed=None, **kwargs)

Initialize the tddft

Parameters

• inputfile (str) -- Name of QE input file, which also contains &inputtddft section.

• commf (object) -- Parallel communicator (Fortran)

• embed (object (Fortran)) -- embed object for QE

tddft_restart(istep=None, **kwargs)

Restart the tddft from previous interrupted run.

Parameters

istep (int) -- Start number of steps, just for output.

update_ions(positions=None, lattice=None, update=0, **kwargs)

update the ions of QE

Parameters

• positions (np.ndarray (n, 3)) -- positions of ions

• lattice (3x3 matrix) -- lattice of ions

• update (int) --

  • 0 : update everything (default)

  • 1 : only update atomic information, not update potential