# fqe.fqe_data_set.FqeDataSet

One of the fundamental data structures in the fqe

## Methods

### apply

View source

Applies an operator specified by the tuple of numpy arrays. The result will be returned as a FqeDataSet object. self is unchanged.

### apply_individual_nbody

View source

Apply function with an individual operator represented in arrays, which can handle spin-nonconserving operators and returns the result

### apply_inplace

View source

Applies an operator specified by the tuple of numpy arrays. The result will be kept in-place.

### apply_inplace_individual_nbody

View source

Apply function with an individual operator represented in arrays, which can handle spin-nonconserving operators

### ax_plus_y

View source

Performs :math:y = ax + y with :math:y being self. The result will be kept inplace.

### calculate_coeff_with_dvec

View source

Generate

.. math:: C_I = \sum_J \langle I|a^\dagger_i aj|J \rangle D^J{ij}

### calculate_dvec

View source

Generate, using self.coeff as C_I,

.. math:: D^{J}_{ij} = \sum_I \langle J|a^\dagger_i a_j|I \rangle C_I

### calculate_dvec_fixed_j

View source

Generate, using self.coeff as C_I, for fixed j

.. math:: D^{J}_{ij} = \sum_I \langle J|a^\dagger_i a_j|I \rangle C_I

### calculate_dvec_with_coeff

View source

Generate

.. math:: D^{J}_{ij} = \sum_I \langle J|a^\dagger_i a_j|I \rangle C_I

### calculate_dvec_with_coeff_fixed_j

View source

Generate, for fixed j,

.. math:: D^{J}_{ij} = \sum_I \langle J|a^\dagger_i a_j|I \rangle C_I

### calculate_evec

View source

Generate

.. math:: E^{J}_{klij} = \sum_I \langle J|a^\dagger_k al|I \rangle D^I{ij}

### evolve_inplace_individual_nbody

View source

This code time-evolves a wave function with an individual n-body generator which is spin-nonconserving. It is assumed that :math:T^2 = 0. Using :math:TT = 0 and :math:TT^\dagger is diagonal in the determinant space, one could evaluate as

.. math:: \exp(-i(T+T^\dagger)t) &= 1 + i(T+T^\dagger)t - \frac{1}{2}(TT^\dagger + T^\dagger T)t^2

     - i\frac{1}{6}(TT^\dagger T + T^\dagger TT^\dagger)t^3 + \cdots \\
&= -1 + \cos(t\sqrt{TT^\dagger}) + \cos(t\sqrt{T^\dagger T})
- iT\frac{\sin(t\sqrt{T^\dagger T})}{\sqrt{T^\dagger T} }
- iT^\dagger\frac{\sin(t\sqrt{TT^\dagger})}{\sqrt{TT^\dagger} }


### fill

View source

Fills all of the data to the value specified

### rdm1

View source

Computes 1-particle RDMs. When bra is specified, it computes a transition RDM

### rdm12

View source

Computes 1- and 2-particle RDMs. When bra is specified, it computes a transition RDMs

### rdm123

View source

Computes 1-, 2-, and 3-particle RDMs. When bra is specified, it computes a transition RDMs

### rdm1234

View source

Computes 1-, 2-, 3-, and 4-particle RDMs. When bra is specified, it computes a transition RDMs

### scale

View source

Scales all of the data by the factor specified

[{ "type": "thumb-down", "id": "missingTheInformationINeed", "label":"Missing the information I need" },{ "type": "thumb-down", "id": "tooComplicatedTooManySteps", "label":"Too complicated / too many steps" },{ "type": "thumb-down", "id": "outOfDate", "label":"Out of date" },{ "type": "thumb-down", "id": "samplesCodeIssue", "label":"Samples / code issue" },{ "type": "thumb-down", "id": "otherDown", "label":"Other" }]
[{ "type": "thumb-up", "id": "easyToUnderstand", "label":"Easy to understand" },{ "type": "thumb-up", "id": "solvedMyProblem", "label":"Solved my problem" },{ "type": "thumb-up", "id": "otherUp", "label":"Other" }]