XAS

References: Iannuzzi2007

Sets the method of choice to calculate core-level excitation spectra. The occupied states from which we calculate the excitation should be specified. Localization of the orbitals may be useful. [Edit on GitHub]

Subsections

Keywords

Keyword descriptions

SECTION_PARAMETERS: logical = F

Lone keyword: T

Usage: &XAS T

controls the activation of core-level spectroscopy simulations [Edit on GitHub]

ADDED_MOS: integer = -1

Usage: ADDED_MOS {integer}

Number of additional MOS added spin up only [Edit on GitHub]

ATOMS_LIST: integer

Keyword can be repeated.

Aliases: AT_LIST

Usage: ATOMS_LIST {integer} {integer} .. {integer}

Indexes of the atoms to be excited. This keyword can be repeated several times (useful if you have to specify many indexes). [Edit on GitHub]

DIPOLE_FORM: enum = VELOCITY

Aliases: DIP_FORM

Usage: DIPOLE_FORM string

Valid values:

  • LENGTH Length form ⟨ i | e r | j ⟩

  • VELOCITY Velocity form ⟨ i | d/dr | j ⟩

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

EPS_ADDED: real = 1.00000000E-005

Usage: EPS_ADDED 1.e-6

target accuracy incalculation of the added orbitals [Edit on GitHub]

MAX_ITER_ADDED: integer = 2999

Usage: MAX_ITER_ADDED 100

maximum number of iteration in calculation of added orbitals [Edit on GitHub]

METHOD: enum = NONE

Aliases: XAS_METHOD

Usage: METHOD TP_HH

Valid values:

  • NONE No core electron spectroscopy

  • TP_HH Transition potential half-hole

  • TP_FH Transition potential full-hole

  • TP_VAL Hole in homo for X-ray emission only

  • TP_XHH Transition potential excited half-hole

  • TP_XFH Transition potential excited full-hole

  • DSCF DSCF calculations to compute the first (core)excited state

  • TP_FLEX Transition potential with generalized core occupation and total number of electrons

Method to be used to calculate core-level excitation spectra [Edit on GitHub]

NGAUSS: integer = 3

Usage: NGAUSS {integer}

Number of gto’s for the expansion of the STO of the type given by STATE_TYPE [Edit on GitHub]

ORBITAL_LIST: integer

Keyword can be repeated.

Aliases: ORBITAL_LIST

Usage: ORBITAL_LIST {integer} {integer} .. {integer}

Indices of the localized orbitals to be excited. This keyword can be repeated several times (useful if you have to specify many indexes). [Edit on GitHub]

OVERLAP_THRESHOLD: real = 1.00000000E+000

Usage: OVERLAP_THRESHOLD 8.e-1

Threshold for including more than one initial core excited state per atom. The threshold is taken relative to the maximum overlap. [Edit on GitHub]

RESTART: logical = F

Lone keyword: T

Usage: RESTART

Restart the excited state if the restart file exists [Edit on GitHub]

SPIN_CHANNEL: integer = 1

Usage: SPIN_CHANNEL 1

# Spin channel of the excited orbital [Edit on GitHub]

Usage: STATE_SEARCH 1

# of states where to look for the one to be excited [Edit on GitHub]

STATE_TYPE: enum = 1S

Aliases: TYPE

Usage: STATE_TYPE 1S

Valid values:

  • 1S 1s orbitals

  • 2S 2s orbitals

  • 2P 2p orbitals

  • 3S 3s orbitals

  • 3P 3p orbitals

  • 3D 3d orbitals

  • 4S 4s orbitals

  • 4P 4p orbitals

  • 4D 4d orbitals

  • 4F 4f orbitals

Type of the orbitals that are excited for the xas spectra calculation [Edit on GitHub]

WFN_RESTART_FILE_NAME: string

Aliases: RESTART_FILE_NAME

Usage: WFN_RESTART_FILE_NAME

Root of the file names where to read the MOS from which to restart the calculation of the core level excited states [Edit on GitHub]

XAS_CORE: real = 5.00000000E-001

Usage: XAS_CORE 0.5

Occupation of the core state in XAS calculation by TP_FLEX. [Edit on GitHub]

XAS_TOT_EL: real = -1.00000000E+000

Usage: XAS_TOT_EL 10

Total number of electrons for spin channel alpha, in XAS calculation by TP_FLEX. If it is a negative value, the number of electrons is set to GS number of electrons minus the amount subtracted from the core state [Edit on GitHub]

XES_CORE: real = 1.00000000E+000

Usage: XES_CORE 0.5

Occupation of the core state in XES calculation by TP_VAL. The HOMO is emptied by the same amount. [Edit on GitHub]

XES_EMPTY_HOMO: logical = F

Lone keyword: T

Usage: XES_EMPTY_HOMO

Set the occupation of the HOMO in XES calculation by TP_VAL. The HOMO can be emptied or not, if the core is still full. [Edit on GitHub]