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from gpaw.fdtd.poisson_fdtd import QSFDTD
from gpaw.fdtd.polarizable_material import (PermittivityPlus,
PolarizableMaterial,
PolarizableSphere)
from gpaw.tddft import photoabsorption_spectrum
from gpaw.mpi import world
import numpy as np
# Nanosphere radius (Angstroms)
radius = 50.0
# Whole simulation cell (Angstroms)
large_cell = np.array([3 * radius, 3 * radius, 3 * radius])
# Permittivity of Gold
# J. Chem. Phys. 135, 084121 (2011); http://dx.doi.org/10.1063/1.3626549
gold = [[0.2350, 0.1551, 95.62],
[0.4411, 0.1480, -12.55],
[0.7603, 1.946, -40.89],
[1.161, 1.396, 17.22],
[2.946, 1.183, 15.76],
[4.161, 1.964, 36.63],
[5.747, 1.958, 22.55],
[7.912, 1.361, 81.04]]
# Initialize classical material
classical_material = PolarizableMaterial()
# Classical nanosphere
classical_material.add_component(
PolarizableSphere(center=0.5 * large_cell,
radius=radius,
permittivity=PermittivityPlus(data=gold)))
# Quasistatic FDTD
qsfdtd = QSFDTD(classical_material=classical_material,
atoms=None,
cells=large_cell,
spacings=[8.0, 1.0],
communicator=world,
remove_moments=(4, 1))
# Run ground state
energy = qsfdtd.ground_state('gs.gpw', nbands=-1)
# Run time evolution
qsfdtd.time_propagation('gs.gpw',
time_step=10,
iterations=1000,
kick_strength=[0.001, 0.000, 0.000],
dipole_moment_file='dm.dat')
# Spectrum
photoabsorption_spectrum('dm.dat', 'spec.dat', width=0.0)
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