ExpMPOEvolution¶
full name: tenpy.algorithms.mpo_evolution.ExpMPOEvolution
parent module:
tenpy.algorithms.mpo_evolution
type: class
Inheritance Diagram
Methods
|
Initialize self. |
|
Calculate |
Run the real-time evolution with the WI/WII approximation. |
|
|
Time evolve by N_steps steps. |
-
class
tenpy.algorithms.mpo_evolution.
ExpMPOEvolution
(psi, model, options)[source]¶ Bases:
object
Time evolution of an MPS using the W_I or W_II approximation for
exp(H dt)
.Ref. [Zaletel2015] described a method to obtain MPO approximations \(W_I\) and \(W_{II}\) for the exponential
U = exp(i H dt)
of an MPO H, implemented inmake_U_I()
andmake_U_II()
. This class uses it for real-time evolution.- Parameters
psi (
MPS
) – Initial state to be time evolved. Modified in place.model (
MPOModel
) – The model representing the Hamiltonian which we want to time evolve psi with.options (dict) – Further optional parameters are described in
ExpMPOEvolution
.
Options
-
config
ExpMPOEvolution
¶ option summary Initial value for :attr:`evolved_time`.
Initial truncation error for :attr:`trunc_err`
Truncation parameters as described in :cfg:config:`truncate`.
How much to print what's being done; higher means print more. [...]
-
option
trunc_params
: dict¶ Truncation parameters as described in
truncate
.
-
option
start_time
: float¶ Initial value for
evolved_time
.
-
option
start_trunc_err
:TruncationError
¶ Initial truncation error for
trunc_err
-
option
-
evolved_time
¶ Indicating how long psi has been evolved,
psi = exp(-i * evolved_time * H) psi(t=0)
.- Type
-
trunc_err
¶ The error of the represented state which is introduced due to the truncation during the sequence of update steps
- Type
-
_U
¶ Exponentiated H_MPO;
- Type
list of
MPO
-
_U_param
¶ A dictionary containing the information of the latest created _U. We won’t recalculate _U if those parameters didn’t change.
- Type
-
run
()[source]¶ Run the real-time evolution with the WI/WII approximation.
Options
-
option
MpoEvolution
.
dt
: float¶ Time step.
-
option
MpoEvolution
.
N_steps
: int¶ Number of time steps dt to evolve
-
option
MpoEvolution
.
approximation
: 'I' or 'II'¶ Specifies which approximation is applied. The default ‘II’ is more precise. See [Zaletel2015] and
make_U()
for more details.
-
option
MpoEvolution
.
order
: int¶ Order of the algorithm. The total error scales as
O(t*dt^order)
. Implemented are order = 1 and order = 2.
-
option