ReferenceState

class adcc.ReferenceState(hfdata, core_orbitals=None, frozen_core=None, frozen_virtual=None, symmetry_check_on_import=False, import_all_below_n_orbs=10)

Bases: libadcc.ReferenceState

Construct a ReferenceState holding information about the employed SCF reference.

The constructed object is lazy and will at construction only setup orbital energies and coefficients. Fock matrix blocks and electron-repulsion integral blocks are imported as needed.

Orbital subspace selection: In order to specify frozen_core, core_orbitals and frozen_virtual, adcc allows a range of specifications including

A number: Just put this number of alpha orbitals and this number of beta orbitals into the respective space. For frozen core and core orbitals these are counted from below, for frozen virtual orbitals, these are counted from above. If both frozen core and core orbitals are specified like this, the lowest-energy, occupied orbitals will be put into frozen core.

A range: The orbital indices given by this range will be put into the orbital subspace.

An explicit list of orbital indices to be placed into the subspace.

A pair of (a) to (c): If the orbital selection for alpha and beta orbitals should differ, a pair of ranges, or a pair of index lists or a pair of numbers can be specified.

Parameters

hfdata – Object with Hartree-Fock data (e.g. a molsturm scf state, a pyscf SCF object or any class implementing the adcc.HartreeFockProvider interface or in fact any python object representing a pointer to a C++ object derived off the adcc::HartreeFockSolution_i.
core_orbitals (int or list or tuple, optional) – The orbitals to be put into the core-occupied space. For ways to define the core orbitals see the description above.
frozen_core (int or list or tuple, optional) – The orbitals to be put into the frozen core space. For ways to define the core orbitals see the description above. For an automatic selection of the frozen core space one may also specify frozen_core=True.
frozen_virtuals (int or list or tuple, optional) – The orbitals to be put into the frozen virtual space. For ways to define the core orbitals see the description above.
symmetry_check_on_import (bool, optional) – Should symmetry of the imported objects be checked explicitly during the import process. This massively slows down the import and has a dramatic impact on memory usage. Thus one should enable this only for debugging (e.g. for testing import routines from the host programs). Do not enable this unless you know what you are doing.
import_all_below_n_orbs (int, optional) – For small problem sizes lazy make less sense, since the memory requirement for storing the ERI tensor is neglibile and thus the flexiblity gained by having the full tensor in memory is advantageous. Below the number of orbitals specified by this parameter, the class will thus automatically import all ERI tensor and Fock matrix blocks.

Examples

To start a calculation with the 2 lowest alpha and beta orbitals in the core occupied space, construct the class as

>>> ReferenceState(hfdata, core_orbitals=2)

or

>>> ReferenceState(hfdata, core_orbitals=range(2))

or

>>> ReferenceState(hfdata, core_orbitals=[0, 1])

or

>>> ReferenceState(hfdata, core_orbitals=([0, 1], [0, 1]))

There is no restriction to choose the core occupied orbitals from the bottom end of the occupied orbitals. For example to select the 2nd and 3rd orbital setup the class as

>>> ReferenceState(hfdata, core_orbitals=range(1, 3))

or

>>> ReferenceState(hfdata, core_orbitals=[1, 2])

If different orbitals should be placed in the alpha and beta orbitals, this can be achievd like so

>>> ReferenceState(hfdata, core_orbitals=([1, 2], [0, 1]))

which would place the 2nd and 3rd alpha and the 1st and second beta orbital into the core space.

Attributes Summary

`density`	Return the Hartree-Fock density in the MO basis
`dipole_moment`	Return the HF dipole moment of the reference state (that is the sum of the electronic and the nuclear contribution.)
`is_aufbau_occupation`	Returns whether the molecular orbital occupation in this reference is according to the Aufbau principle (lowest-energy orbitals are occupied)
`mospaces`	The MoSpaces object supplied on initialisation
`timer`	Obtain the timer object of this class.

Methods Summary

to_qcvars([properties, recurse])

Return a dictionary with property keys compatible to a Psi4 wavefunction or a QCEngine Atomicresults object.

Attributes Documentation

density: Return the Hartree-Fock density in the MO basis

dipole_moment: Return the HF dipole moment of the reference state (that is the sum of the electronic and the nuclear contribution.)

is_aufbau_occupation: Returns whether the molecular orbital occupation in this reference is according to the Aufbau principle (lowest-energy orbitals are occupied)

mospaces

timer

Methods Documentation

to_qcvars(properties=False, recurse=False): Return a dictionary with property keys compatible to a Psi4 wavefunction or a QCEngine Atomicresults object.