Quantum ESPRESSO as an AMS engine: Antiferromagnetic FeO

Note: This example requires AMS2023 and that you have installed Quantum ESPRESSO from the AMS package manager.

See also

Documentation for QE in AMS

Example usage: (Download QE_AMS_AFM_HubbardU.py)

#!/usr/bin/env amspython
from scm.plams import *

def main():
    init()

    mol = get_system()
    s = get_settings()
    
    # Note: do NOT give the job the name "quantumespresso", as that will cause file name clashes
    job = AMSJob(molecule=mol, settings=s, name='afm-FeO')
    print(job.get_input())

    job.run()

    print("Final energy (hartree)")
    print(job.results.get_energy())

    finish()

def get_settings() -> Settings:
    s = Settings()

    s.runscript.preamble_lines = ['export SCM_DISABLE_MPI=1']
    #s.runscript.preamble_lines.append('export QE_STARCMD="custom_start_command"')

    s.input.ams.Task = 'SinglePoint'

    pp_dict = {
        'Fe1' : 'QE/Fe.pbe-sp-van_ak.UPF',
        'Fe2' : 'QE/Fe.pbe-sp-van_ak.UPF',
        'O'   : 'QE/O.pbe-van_ak.UPF'
    }
    # Use the ._1 syntax for unstructured blocks like Pseudopotentials
    s.input.QuantumEspresso.Pseudopotentials._1 = pseudopotentials_block(pp_dict)

    # Use ._h and ._1 for unstructured blocks like K_Points
    s.input.QuantumEspresso.K_Points._h = 'automatic'
    s.input.QuantumEspresso.K_Points._1 = '6 6 6 0 0 0'

    # Hubbard U specified in the new QE 7.1 format (different from QE 7.0)
    s.input.QuantumEspresso.Hubbard._h = 'ortho-atomic'
    s.input.QuantumEspresso.Hubbard._1 = '''
        U Fe1-3d 4.6
        U Fe2-3d 4.6
    '''

    # When initializing many keys inside the same block
    # it can be convenient to group them like this
    s.input.QuantumEspresso.System = Settings(
        ecutwfc = 40.0,
        ecutrho = 240.0,
        occupations = 'smearing',
        smearing = 'gaussian',
        degauss = 0.02,
        nspin = 2,
        starting_magnetization = [ 'Fe1 1.0', 'Fe2 -1.0' ]
    )

    # You may also just use the normal PLAMS Settings dot notation 
    s.input.QuantumEspresso.Electrons.conv_thr = 1.0e-8
    s.input.QuantumEspresso.Electrons.mixing_beta = 0.3

    return s


def get_system() -> Molecule:
    """

    Returns a PLAMS Molecule for FeO with the QE.Label properties set to 'Fe1'
    and 'Fe2' for the two Fe atoms

    """

    d = 4.33
    mol = Molecule()
    mol.add_atom(Atom(symbol='Fe', coords=(0, 0, 0)))
    mol.add_atom(Atom(symbol='Fe', coords=(d/2, d/2, 0)))
    mol.add_atom(Atom(symbol='O', coords=(0, d/2, 0)))
    mol.add_atom(Atom(symbol='O', coords=(d/2, 0, 0)))

    mol.lattice = [[d, 0, 0], [0, d, 0], [d/2, 0, d/2]]

    mol[1].properties.QE.Label='Fe1'
    mol[2].properties.QE.Label='Fe2'

    return mol

def pseudopotentials_block(pp_dict):
    """
    Transforms a dictionary to a single string
    """

    return "\n     ".join(f'{k} {v}' for k,v in pp_dict.items())


if __name__ == '__main__':
    main()