# Set up lattice
lattice = SimpleCubic(3.731*Angstrom)

# Define elements
elements = [Silver, Cerium]

# Define coordinates
cartesian_coordinates = [[ 0.    ,  0.    ,  0.    ],
                         [ 1.8655,  1.8655,  1.8655]]*Angstrom

# Set up configuration
bulk_configuration = BulkConfiguration(
    bravais_lattice=lattice,
    elements=elements,
    cartesian_coordinates=cartesian_coordinates
    )

bulk_configuration.setCalculator(LCAOCalculator())

# Run the optimization
constraints = [FixStrain(x=True, y=False, z=True)]
bulk_configuration = OptimizeGeometry(
        bulk_configuration,
        constraints=constraints,
        )