qstack.fields.excited

Excited state density and property analysis.

qstack.fields.excited.exciton_properties(mol, hole, part)[source]

Compute the ab initio or decomposed/predicted hole-particle distance, the hole size, and the particle size.

Distance is defined as |<r>_hole - <r>_part|, and size as sqrt(<r^2> - <r>^2).

Parameters:

  • mol (pyscf Mole) – pyscf Mole object.

  • hole (numpy ndarray) – Hole density matrix in AO basis (2D) or decomposition coefficients (1D).

  • part (numpy ndarray) – Particle density matrix in AO basis (2D) or decomposition coefficients (1D).

Returns:

  • hole-particle distance,

  • hole size,

  • particle size.

Return type:

Tuple of floats

Raises:

RuntimeError – If the dimensions of hole and part do not match or are not 1D or 2D.

qstack.fields.excited.exciton_properties_c(mol, hole, part)[source]

Compute the decomposed/predicted hole-particle distance, the hole size, and the particle size.

Parameters:

  • mol (pyscf Mole) – pyscf Mole object.

  • hole (numpy ndarray) – Hole AO density decomposition coefficiants.

  • part (numpy ndarray) – Particle density decomposition coefficiants.

Returns:

  • hole-particle distance,

  • hole size,

  • particle size.

Return type:

Tuple of floats

qstack.fields.excited.exciton_properties_dm(mol, hole, part)[source]

Compute the ab initio hole-particle distance, the hole size, and the particle size.

Parameters:

  • mol (pyscf Mole) – pyscf Mole object.

  • hole (numpy ndarray) – Hole density matrix.

  • part (numpy ndarray) – Particle density matrix.

Returns:

  • hole-particle distance,

  • hole size,

  • particle size.

Return type:

Tuple of floats

qstack.fields.excited.get_cis(mf, nstates)[source]

Run a CIS (Configuration interaction singles) / TDA (Tamm-Dancoff approximation) computation.

Parameters:

  • mf – Pyscf mean-field object.

  • nstates (int) – Number of excited states to compute.

Returns:

Converged TDA/CIS computation object with excited state information.

Return type:

TDA object

qstack.fields.excited.get_cis_tdm(td)[source]

Extract transition density matrices from TDA/CIS calculation.

Parameters:

td – TDA/CIS calculation object containing excitation amplitudes.

Returns:

Array of transition density matrices for all computed states.

Return type:

numpy ndarray

qstack.fields.excited.get_holepart(mol, x, coeff)[source]

Compute the hole and particle density matrices (in AO basis) for a selected state.

Parameters:

  • mol (pyscf Mole) – pyscf Mole object.

  • x (numpy ndarray) – Response vector (occ×virt) normalized to 1.

  • coeff (numpy ndarray) – Ground-state molecular orbital vectors.

Returns:

Two numpy ndarrays containing the hole density matrices and the particle density matrices respectively.

qstack.fields.excited.get_transition_dm(mol, x_mo, coeff)[source]

Compute the transition density matrix for a selected state.

Parameters:

  • mol (pyscf Mole) – pyscf Mole object.

  • x_mo (numpy ndarray) – Response vector (occ×virt) normalized to 1.

  • coeff (numpy ndarray) – Ground-state molecular orbital vectors.

Returns:

transition density matrix.

Return type:

numpy ndarray