# XAS_TDP

XAS simulations using linear-response TDDFT. Excitation from specified core orbitals are considered one at a time. In case of high symmetry structures, donor core orbitals should be localized. [Edit on GitHub]

Subsections

- DONOR_STATES
- GW2X
- KERNEL
- OT_SOLVER
- PRINT

## Keywords

- SECTION_PARAMETERS

- CHECK_ONLY

- DIPOLE_FORM

- ENERGY_RANGE

- EPS_FILTER

- EPS_PGF_XAS

- EXCITATIONS

- GRID

- N_EXCITED

- QUADRUPOLE

- RESTART_FROM_FILE

- SPIN_DIPOLE

- SPIN_ORBIT_COUPLING

- TAMM_DANCOFF

- XYZ_DIPOLE

## Keyword descriptions

SECTION_PARAMETERS: logical = F

  Lone keyword: `T`

  Usage: &TDP_XAS {logical}

  controls the activation of XAS simulations with linear response TDDFT. [Edit on GitHub]

CHECK_ONLY: logical = F

  Lone keyword: `T`

  Usage: CHECK_ONLY {logical}

  This keyword defines whether the full calculation should be done or not. If set to .TRUE., only the determination of donor MOs is conducted. This run option allows for cheap verification of the input parameters [Edit on GitHub]

DIPOLE_FORM: enum = VELOCITY

  Aliases: DIP_FORM

  Usage: DIPOLE_FORM {string}

  Valid values:

  - `LENGTH` Length form ⟨ 0 | e r | n ⟩

  - `VELOCITY` Velocity form ⟨ 0 | d/dr | n ⟩

  Type of integral to get the oscillator strengths in the dipole approximation [Edit on GitHub]

ENERGY_RANGE: real = -1.00000000E+000

  Aliases: E_RANGE

  Usage: ENERGY_RANGE {real}

  The energy range in eV for which excitations are considered. Only excitated states within the range of: first excitation energy + ENERGY_RANGE are kept. If ENERGY_RANGE and N_EXCITED are specified, the former has priority. Negative values are ignored and N_EXCITED takes over. [Edit on GitHub]

EPS_FILTER: real = 1.00000000E-010

  Aliases: EPS_FILTER_MATRIX

  Usage: EPS_FILTER {real}

  Mentions: ⭐X-Ray Absorption from TDDFT

  The threshold used for sparse matrix operations [Edit on GitHub]

EPS_PGF_XAS: real

  Aliases: EPS_PGF ,EPS_PGF_XAS_TDP

  Usage: EPS_PGF_XAS {real}

  Mentions: ⭐X-Ray Absorption from TDDFT

  The threshold used to determine the spacial extent of all primitive Gaussian functions used for the construction of neighbor lists in the XAS_TDP method. By default, takes the value of QS%EPS_PGF_ORB. Useful if the former value is tiny due to possible ground state HFX contributions. [Edit on GitHub]

EXCITATIONS: enum = RCS_SINGLET

  Keyword can be repeated.

  Aliases: EXCITATION

  Usage: EXCITATIONS {string}

  Valid values:

  - `RCS_SINGLET` Singlet excitation on top of restricted closed-shell ground state

  - `RCS_TRIPLET` Triplet excitation on top of restricted closed-shell ground state

  - `OS_SPIN_CONS` Spin-conserving excitations on top of open-shell ground state

  - `OS_SPIN_FLIP` Spin-flip excitation on top of open-shell ground state

  Mentions: ⭐X-Ray Absorption from TDDFT

  Specify the type of excitation to consider. In case of a resctricted closed-shell ground state calculation, RCS_SINGLET or/and RCS_TRIPLET can be chosen. In case of a open-shell ground state calculation (either UKS or ROKS), standard spin conserving excitation (OS_SPIN_CONS) or/and spin-flip excitation (OS_SPIN_FLIP) can be chosen. [Edit on GitHub]

GRID: string[3]

  Keyword can be repeated.

  Aliases: ATOMIC_GRID

  Usage: GRID {string} {integer} {integer}

  Mentions: ⭐X-Ray Absorption from TDDFT

  Specification of the atomic angular and radial grids for a given atomic kind. This keyword can/should be repeated for each excited kind. The default grid dimensions are those set for the GAPW ground state calculation. These grids are used for the xc-kernel integration. Usage: GRID < KIND > < LEBEDEV_GRID > < RADIAL_GRID > [Edit on GitHub]

N_EXCITED: integer = -1

  Aliases: N_ROOTS

  Usage: N_EXCITED {integer}

  The number of excited states to compute per donor molecular orbital. (e.g. if 2p excitations, 3*N_EXCITED excited states are considered). If N_EXCITED is set to -1, all excitations are considered [Edit on GitHub]

QUADRUPOLE: logical = F

  Aliases: DO_QUADRUPOLE ,DO_QUAD ,QUAD

  Lone keyword: `T`

  Usage: QUADRUPOLE {logical}

  Compute the electric quadrupole contribution to the oscillator strenghts (in the length representation with the origin set on the relevant excited atom) [Edit on GitHub]

RESTART_FROM_FILE: string[ ]

  Aliases: RESTART_FILENAME ,RST_FILENAME ,RESTART_FILE ,RST_FILE

  Usage: RESTART_FROM_FILE <FILENAME>

  By providing a RESTART file containing the linear-response orbitals and excitations energies from a previous calculation, all computations are skipped except for the corresponding PDOS and/or CUBE file printing as defined in the PRINT subsection. Basis sets and geometry need to be consistent. [Edit on GitHub]

SPIN_DIPOLE: logical = F

  Aliases: DIPOLE_SPIN

  Lone keyword: `T`

  Usage: SPIN_DIPOLE {logical}

  Whether the detailed contributions of the dipole oscillator strengths for alpha and beta spins should be printed. [Edit on GitHub]

SPIN_ORBIT_COUPLING: logical = F

  Aliases: SOC

  Lone keyword: `T`

  Usage: SOC {logical}

  Mentions: ⭐X-Ray Absorption from TDDFT

  Whether spin-orbit coupling should be added. Note: only applies for spin-restricted calculations with singlet and triplet excitations OR spin-unrestricted calculations with both spin-conserving and spin-flip. [Edit on GitHub]

TAMM_DANCOFF: logical = T

  Aliases: TDA

  Lone keyword: `T`

  Usage: TAMM_DANCOFF {logical}

  Whether the Tamm-Dancoff approximation should be used. [Edit on GitHub]

XYZ_DIPOLE: logical = F

  Aliases: DIPOLE_XYZ

  Lone keyword: `T`

  Usage: XYZ_DIPOLE {logical}

  Whether the detailed contributions of the dipole oscillator strengths along the X,Y,Z directions should be printed. [Edit on GitHub]