# stability

Performs SCF wavefunction stability analysis. This command can appear in the global context.

### Options

convergence

Convergence threshold for the iterative subspace solver, tested on on the infinity norm of the residual vectors.

• The type is real
• The default is 1e-6
• The value must be positive
frozen_core

Whether to use frozen-core approximation.

• The type is bool
• The default is false
incore

Flag for whether to construct the response matrix explicitly.

• The type is bool
• The default is false
• The value must be one of:
• true - Construct the response matrix explicitly and store it in memory. This option is only available for response calculations based on a Hartree-Fock wavefunction, and should be used only for testing purposes.
• false - Do not construct the response matrix explicitly, but compute the matrix-vector product instead. This will require iterative solvers.
linear_dependency_threshold

Threshold for removing linearly dependent vectors based on the square of singular values of the matrix.

• The type is real
• The default is 1e-10
• The value must be positive
load_transition_density

Load the AO transition density matrix from file (in arma::arma_binary) format.

• The type is string
• There is no default value.
max_iter

Maximum number of iterations for the iterative subspace solver.

• The type is int
• The default is 128
• The value must be positive
n_states

Number of eigenvectors of the Hessian to be calculated.

• The type is int
• The default is 1
• The value must be nonnegative
name

Specify the name of a set of results.

This option is deprecated.

• The type is string
• There is no default value.
orthonormal_threshold

Threshold for orthonormalization of the suspace vectors.

• The type is real
• The default is 1e-10
• The value must be positive
print_level

Print level.

• The type is int
• There is no default value.
• The value must be one of:
• -2 - No output
• -1 - Minimum output
• 0 - Output that doesn't scale with system size
• 1 - Output that scales linearly with system size
• 2 - (Debugging) output that scales quadratically with system size
• 3 - (Debugging) output that scales cubically with system size
save_transition_density

Save the AO transition density matrix to file (in arma::arma_binary) format.

• The type is string
• There is no default value.
spin

Constrain the spin state for the wavefunction stability testing or reoptimization.

• The type is string
• The default is singlet
• The value must be one of:
• singlet - Constrain the wevefunction stability testing or reoptimization to be spin-singlet. Only effective for closed-shell SCF.
• triplet - Constrain the wevefunction stability testing or reoptimization to be spin-triplet. Only effective for closed-shell SCF.
• unrestricted - Constrain the wevefunction stability testing or reoptimization to be spin-unrestricted.