# EvolutionProblem

*class *`EvolutionProblem(hamiltonian, time, initial_state=None, aux_operators=None, truncation_threshold=1e-12, t_param=None, param_value_dict=None)`

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The EvolutionProblem class has been superseded by the `qiskit.algorithms.time_evolvers.TimeEvolutionProblem`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`

) – The Hamiltonian under which to evolve the system.**time**(`float`

) – Total time of evolution.**initial_state**(`Union`

[`StateFn`

,`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`

]],`Dict`

[`str`

,`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`

]) – Time parameter in case of a time-dependent Hamiltonian. This free parameter must be within the`hamiltonian`

.**param_value_dict**(`Optional`

[`Dict`

[`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

`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`

## Attributes

### time

Returns time.

**Return type**

`float`