# -*- coding: utf-8 -*-
# -------------------------------------------------------------
# Bulk Configuration
# -------------------------------------------------------------

# Set up lattice
lattice = SimpleTetragonal(4.593*Angstrom, 2.959*Angstrom)

# Define elements
elements = [Titanium, Titanium, Oxygen, Oxygen, Oxygen, Oxygen]

# Define coordinates
fractional_coordinates = [[ 0.    ,  0.    ,  0.    ],
                          [ 0.5   ,  0.5   ,  0.5   ],
                          [ 0.3051,  0.3051,  0.    ],
                          [ 0.6949,  0.6949,  0.    ],
                          [ 0.8051,  0.1949,  0.5   ],
                          [ 0.1949,  0.8051,  0.5   ]]

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

# -------------------------------------------------------------
# Calculator
# -------------------------------------------------------------
k_point_sampling = MonkhorstPackGrid(
    na=3,
    nb=3,
    nc=5,
    )
numerical_accuracy_parameters = NumericalAccuracyParameters(
    k_point_sampling=k_point_sampling,
    density_mesh_cutoff=125.0*Hartree,
    )

calculator = LCAOCalculator(
    numerical_accuracy_parameters=numerical_accuracy_parameters,
    )

bulk_configuration.setCalculator(calculator)
nlprint(bulk_configuration)
bulk_configuration.update()
nlsave('Rutile.hdf5', bulk_configuration)

# -------------------------------------------------------------
# Optimize Geometry
# -------------------------------------------------------------
constraints = [BravaisLatticeConstraint()]

bulk_configuration = OptimizeGeometry(
    bulk_configuration,
    max_forces=0.05*eV/Ang,
    max_stress=0.1*GPa,
    max_steps=200,
    max_step_length=0.2*Ang,
    constraints=constraints,
    trajectory_filename=None,
    optimizer_method=LBFGS(),
)
nlsave('Rutile.hdf5', bulk_configuration)
nlprint(bulk_configuration)