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---
title: EvolutionProblem
description: API reference for qiskit.algorithms.EvolutionProblem
in_page_toc_min_heading_level: 1
python_api_type: class
python_api_name: qiskit.algorithms.EvolutionProblem
---
# EvolutionProblem
<Class id="qiskit.algorithms.EvolutionProblem" isDedicatedPage={true} github="https://github.com/qiskit/qiskit/tree/stable/0.22/qiskit/algorithms/evolvers/evolution_problem.py" signature="EvolutionProblem(hamiltonian, time, initial_state=None, aux_operators=None, truncation_threshold=1e-12, t_param=None, param_value_dict=None)" modifiers="class">
Bases: `object`
Pending deprecation: Evolution problem class.
The EvolutionProblem class has been superseded by the `qiskit.algorithms.time_evolvers.TimeEvolutionProblem` class. This class will be deprecated in a future release and subsequently removed after that.
This class is the input to time evolution algorithms and must contain information on the total evolution time, a quantum state to be evolved and under which Hamiltonian the state is evolved.
**Parameters**
* **hamiltonian** ([`OperatorBase`](qiskit.opflow.OperatorBase "qiskit.opflow.operator_base.OperatorBase")) The Hamiltonian under which to evolve the system.
* **time** (`float`) Total time of evolution.
* **initial\_state** (`Union`\[[`StateFn`](qiskit.opflow.state_fns.StateFn "qiskit.opflow.state_fns.state_fn.StateFn"), [`QuantumCircuit`](qiskit.circuit.QuantumCircuit "qiskit.circuit.quantumcircuit.QuantumCircuit"), `None`]) The quantum state to be evolved for methods like Trotterization. For variational time evolutions, where the evolution happens in an ansatz, this argument is not required.
* **aux\_operators** (`Union`\[`List`\[`Optional`\[[`OperatorBase`](qiskit.opflow.OperatorBase "qiskit.opflow.operator_base.OperatorBase")]], `Dict`\[`str`, [`OperatorBase`](qiskit.opflow.OperatorBase "qiskit.opflow.operator_base.OperatorBase")], `None`]) Optional list of auxiliary operators to be evaluated with the evolved `initial_state` and their expectation values returned.
* **truncation\_threshold** (`float`) Defines a threshold under which values can be assumed to be 0. Used when `aux_operators` is provided.
* **t\_param** (`Optional`\[[`Parameter`](qiskit.circuit.Parameter "qiskit.circuit.parameter.Parameter")]) Time parameter in case of a time-dependent Hamiltonian. This free parameter must be within the `hamiltonian`.
* **param\_value\_dict** (`Optional`\[`Dict`\[[`Parameter`](qiskit.circuit.Parameter "qiskit.circuit.parameter.Parameter"), `complex`]]) Maps free parameters in the problem to values. Depending on the algorithm, it might refer to e.g. a Hamiltonian or an initial state.
**Raises**
**ValueError** If non-positive time of evolution is provided.
## Methods
### validate\_params
<Function id="qiskit.algorithms.EvolutionProblem.validate_params" signature="EvolutionProblem.validate_params()">
Checks if all parameters present in the Hamiltonian are also present in the dictionary that maps them to values.
**Raises**
**ValueError** If Hamiltonian parameters cannot be bound with data provided.
**Return type**
`None`
</Function>
## Attributes
### time
<Attribute id="qiskit.algorithms.EvolutionProblem.time">
Returns time.
**Return type**
`float`
</Attribute>
</Class>