# Ising

An Ising Hamiltonian operator.

## Class Constructor

Constructs a new Ising given a hilbert space, a transverse field, and (if specified) a coupling constant.

Argument Type Description
hilbert netket.hilbert.Hilbert Hilbert space the operator acts on.
h float The strength of the transverse field.
J float=1.0 The strength of the coupling. Default is 1.0.

### Examples

Constructs an Ising operator for a 1D system.

>>> import netket as nk
>>> g = nk.graph.Hypercube(length=20, n_dim=1, pbc=True)
>>> hi = nk.hilbert.Spin(s=0.5, graph=g)
>>> op = nk.operator.Ising(h=1.321, hilbert=hi, J=0.5)
>>> print(op.hilbert.size)
20



## Class Methods

### get_conn

Member function finding the connected elements of the Operator. Starting from a given visible state v, it finds all other visible states v’ such that the matrix element O(v,v’) is different from zero. In general there will be several different connected visible units satisfying this condition, and they are denoted here v’(k), for k=0,1…N_connected.

Argument Type Description
v numpy.ndarray[float64[m, 1]] A constant reference to the visible configuration.

## Properties

Property Type Description
hilbert netket.hilbert.Hilbert Hilbert space of operator.