def sample(struct, size, rescale=20, nr_processes=1, elec_field=0.0):
def pbc_func(unit_cell_coords, orbital_ind):
x, y, z = unit_cell_coords
return (x % size[0], y % size[1], z), orbital_ind
nsite = struct.nsite
site_set = siteset(nsite, size)
latt = lattice(struct)
if os.path.isfile('sample.hdf5'):
print('Reading sample ...')
sp = tipsi.Sample(latt,
site_set,
pbc_func,
nr_processes=nr_processes,
read_from_file='sample.hdf5')
print('Read done')
else:
print('Constructing sample from scratch ...')
sp = tipsi.Sample(latt, site_set, pbc_func, nr_processes=nr_processes)
hop_dict = SparseHopDict(nsite)
hop_dict.dict = struct.hoppings_2to3()
sp.add_hop_dict(hop_dict)
sp.save()
sp.rescale_H(rescale)
return sp
def square(width: int, a: float, t: float, periodic: bool) -> tipsi.Sample:
vectors = [[a, 0, 0], [0, a, 0]]
orbital_coords = [[0, 0, 0]]
lattice = tipsi.builder.Lattice(vectors, orbital_coords)
site_set = tipsi.builder.SiteSet()
for i in range(width):
for j in range(width):
site_set.add_site((i, j, 0))
hop_dict = tipsi.builder.HopDict()
hop_dict.set((1, 0, 0), t)
hop_dict.set((0, 1, 0), t)
if periodic:
def pbc_func(unit_cell_coords, orbital):
n0, n1, n2 = unit_cell_coords
return (n0 % width, n1 % width, n2), orbital
else:
pbc_func = tipsi.builder.bc_default
sample = tipsi.Sample(lattice, site_set, pbc_func)
sample.add_hop_dict(hop_dict)
return sample
def sample(struct, rescale=30., nr_processes=1):
nsite = len(struct.coords)
latt = lattice(struct.coords)
site_set = siteset(nsite)
if os.path.isfile('sample.hdf5'):
sp = tipsi.Sample(latt, site_set, nr_processes=nr_processes, read_from_file='sample.hdf5')
else:
sp = tipsi.Sample(latt, site_set, nr_processes=nr_processes)
t0 = time.time()
hop_dict = hopdict(struct, elec_field=elec_field)
t1 = time.time()
print('hop % s' % (t1-t0))
del struct
sp.add_hop_dict(hop_dict)
sp.save()
sp.rescale_H(rescale)
return sp
def carpet(start_width, iteration, lattice_constant, hopping_value):
lattice = square_lattice(lattice_constant)
sites = carpet_sites(start_width, iteration)
sample = tipsi.Sample(lattice, sites, bc_func=lambda p, o: (p, o))
sample.add_hop_dict(carpet_hoppings(hopping_value))
return sample