forte2.scf.scf_utils#
Module Contents#
- forte2.scf.scf_utils.minao_initial_guess(system, H)#
Generate a superposition of atomic potentials (SAP) initial guess for the SCF procedure S. Lehtola, J. Chem. Theory Comput. 15, 1593-1604 (2019), arXiv:1810.11659. For details, see https://doi.org/10.1063/5.0004046
- Parameters:
- systemforte2.System
The system object containing the atoms and basis set.
- HNDArray
The Fock matrix.
- SNDArray
The overlap matrix.
- Returns:
- NDArray
The initial MO guess for the SCF procedure.
- forte2.scf.scf_utils.core_initial_guess(system: forte2.system.System, H)#
Generate an initial guess by diagonalizing the core Hamiltonian.
- Parameters:
- systemforte2.System
The system object containing the atoms and basis set.
- HNDArray
The core Hamiltonian matrix.
- Returns:
- NDArray
The initial MO guess for the SCF procedure.
- forte2.scf.scf_utils.guess_mix(C, homo_idx, mixing_parameter=np.pi / 4)#
Induce the breaking of S^2 symmetry for UHF ms=0.0 calculations. This is helpful for obtaining proxies for open-shell singlets, for example.
- Parameters:
- CNDArray
The MO coefficients.
- homo_idxint
The index of the highest occupied molecular orbital (HOMO).
- mixing_parameterfloat, optional
The mixing parameter for the Givens rotation.
- twocompbool, optional
Whether the system is two-component.
- Returns:
- NDArray
The modified MO coefficients.
Notes
See Szabo and Ostlund Ch. 3.8.7.
- forte2.scf.scf_utils.guess_mix_ghf(C, ha, hb, la, lb, mixing_parameter=np.pi / 4)#
Induce the breaking of S^2 symmetry for UHF ms=0.0 calculations. This is helpful for obtaining proxies for open-shell singlets, for example.
- Parameters:
- CNDArray
The MO coefficients.
- haint
The index of the highest occupied alpha(-like) orbital.
- hbint
The index of the highest occupied beta(-like) orbital.
- laint
The index of the lowest unoccupied alpha(-like) orbital.
- lbint
The index of the lowest unoccupied beta(-like) orbital.
- mixing_parameterfloat, optional
The mixing parameter for the Givens rotation.
- Returns:
- NDArray
The modified MO coefficients.
Notes
See Szabo and Ostlund Ch. 3.8.7.
- forte2.scf.scf_utils.alpha_beta_mix(C, mixing_parameter=0.1)#
Induce the breaking of S_z symmetry for GHF calculations. This function explicitly mixes the degenerate alpha and beta MOs, which results in non-vanishing D_ab/D_ba density matrix elements.
- Parameters:
- CNDArray
The MO coefficients.
- mixing_parameterfloat, optional
The mixing parameter for the Givens rotation.
- Returns:
- NDArray
The modified MO coefficients.
- forte2.scf.scf_utils.break_complex_conjugation_symmetry(C, pert_strength=0.1)#
Break the time-reversal/complex conjugation symmetry of the MO coefficients. A random phase is applied to each AO (cannot be MO as it would not change the density matrix).
- Parameters:
- CNDArray
The MO coefficients.
- pert_strengthfloat, optional
The strength of the perturbation (in radians).
- Returns:
- NDArray
The modified MO coefficients.