def evolve(self):
"""
Perform a Trotterized time evolution step by tau. Compress after each dot product or after each sweep
through the chain. Renormalizes state after one full timestep due to compression.
:return:
"""
overlap = self.base_overlap
last_start_at = self.system_index
if not self.canonicalize_every_step:
canonicalize_to(self.psi_t, to_cform=self.to_cform)
for (start_at, trotter_mpo) in self.propagator.trotter_steps:
self.psi_t = mp.partialdot(trotter_mpo,
self.psi_t,
start_at=start_at,
axes=self.axes)
if self.full_compression:
if start_at == self.propagator.L - 2 or start_at == 0:
# Compress after a full sweep
if start_at != last_start_at:
overlap *= self.psi_t.compress(
**self.state_compression_kwargs)
else:
if len(trotter_mpo) > 1:
self.lc.compress(self.psi_t, start_at)
if self.final_compression:
overlap *= self.psi_t.compress(**self.state_compression_kwargs)
else:
if not self.canonicalize_every_step:
canonicalize_to(self.psi_t, to_cform=self.to_cform)
self._normalize_state()
self.cumulative_overlap *= overlap
self.last_overlap = overlap
self.trotter_error += self.propagator.step_trotter_error
self.stepno += 1
def stepsize(A, g, X):
# its actually not a projection, but it works surprisingly
proj = mp.MPArray(
[_local_contraction(l)[None, ..., None] for l in X.lt[:-1]])
g = mp.partialdot(proj, g, start_at=0)
g.compress(**compargs)
return stepfun(A, g, None)
def stepsize(A, g, X):
X.normalize(left=len(X) - 1)
# get the left-eigenvectors
Us, _ = X.split(len(X) - 2)
Us = Us.reshape([s + (1, ) for s in Us.pdims[:-1]] + [Us.pdims[-1]])
proj = mp.dot(Us.conj(), Us, axes=(1, 1))
g = mp.partialdot(proj, g, start_at=0)
g.compress(**compargs)
return stepfun(A, g, _)
def evolve(self):
"""
Perform a Trotterized time evolution step by tau. Compress after each dot product or after each sweep
through the chain. Renormalize state after one full timestep due to compression.
:return:
"""
overlap = self.base_overlap
last_start_at = self.system_index
if not self.canonicalize_every_step:
canonicalize_to(self.psi_t, to_cform=self.to_cform)
for (start_at, trotter_mpo) in self.propagator.trotter_steps:
self.psi_t = mp.partialdot(trotter_mpo,
self.psi_t,
start_at=start_at,
axes=self.axes)
if self.full_compression:
if (start_at == self.propagator.L - 2
or start_at == 0) and start_at != last_start_at:
# Compress after a full sweep
overlap *= self.psi_t.compress(
**self.state_compression_kwargs)
else:
if len(trotter_mpo) > 1:
self.lc.compress(self.psi_t, start_at)
if (start_at == self.propagator.L - 2
or start_at == 0) and start_at != last_start_at:
self.pmps_compression_step += 1
if self.pmps_compression_step - 1 == self.compress_sites_step:
compress_pmps_sites(self.psi_t,
relerr=self.compress_sites_relerr,
rank=self.compress_sites_rank,
stable=self.compress_sites_stable,
to_cform=self.to_cform)
self.pmps_compression_step = 1
last_start_at = start_at
if self.final_compression:
overlap *= self.psi_t.compress(**self.state_compression_kwargs)
else:
if not self.canonicalize_every_step:
canonicalize_to(self.psi_t, to_cform=self.to_cform)
self._normalize_state()
self.cumulative_overlap *= overlap
self.last_overlap = overlap
if self.system_index == 0:
# reset by one, because next propagation step starts at the edge of chain and increments counter immediately
self.pmps_compression_step -= 1
self.trotter_error += self.propagator.step_trotter_error
self.stepno += 1