td

Time-dependent linear response theory for excited states. This command can appear in the global context.

Subcommands

• dft
• emft
• structure
• xtb

Options

cis

Flag for whether the excited states are computed from Configutation Interaction Singles (CIS) or Tamm-Dancoff Approximation (TDA).

• The type is bool
• The default is false
• The value must be one of:
  • true - Do CIS/TDA for excited states.
  • false - Do Random-Phase Approximation (RPA)/Time-Dependent Density Functional Theory (TDDFT) for excited states.

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

min_excitation_energy

Only calculate excited states with excitation energy (in eV) greater than the specified value.

• The type is real
• There is no default value.
• The value must be nonnegative

n_states

Number of excited states to be calculated.

• The type is int
• The default is 3
• 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.

select_hole

Selectively converge the excited state with which the excitations are from the specified hole (i.e. occupied) orbitals.

• The type is [int]
• There is no default value.

spin

Specify spin of the excited states. If no input value is specified, the program will assign default value based on the spin of the reference calculation: for restricted closed-shell reference state, the default spin for excited states will be singlet; otherwise, the default spin will be mixed.

• The type is string
• There is no default value.
• The value must be one of:
  • singlet - Solve for Singlet excited states only. Only effective for closed-shell reference. This is the default for a closed-shell reference state.
  • triplet - Solve for Triplet excited states only. Only effective for closed-shell reference.
  • mixed - Solve for excited states of all POSSIBLE spin. This is the default for an unrestriced open-shell reference state. For a closed-shell reference, this will give both singlet and triplet excited states;