# SciPyImaginaryEvolver

*class *`qiskit.algorithms.SciPyImaginaryEvolver(num_timesteps)`

Bases: `ImaginaryTimeEvolver`

Classical Evolver for imaginary time evolution.

Evolves an initial state $|\Psi\rangle$ for an imaginary time $\tau = it$ under a Hamiltonian $H$, as provided in the `evolution_problem`

. Note that the precision of the evolver does not depend on the number of timesteps taken.

**Parameters**

**num_timesteps** (*int*) – The number of timesteps in the simulation.

**Raises**

**ValueError** – If num_timesteps is not a positive integer.

## Methods

### evolve

`evolve(evolution_problem)`

Perform imaginary time evolution $\exp(-\tau H)|\Psi\rangle$.

Evolves an initial state $|\Psi\rangle$ for an imaginary time $\tau$ under a Hamiltonian $H$, as provided in the `evolution_problem`

.

**Parameters**

**evolution_problem** (*TimeEvolutionProblem*) – The definition of the evolution problem.

**Returns**

Evolution result which includes an evolved quantum state.

**Return type**