# PERIODIC_EFIELD

Section can be repeated.

References: Souza2002, Umari2002

parameters for finite periodic electric field computed using the Berry phase approach. IMPORTANT: Can only be used in combination with OT. Can not be used in combination with RTP or EMD, e.g. RESTART_RTP has to be .FALSE. when restarting the job. [Edit on GitHub]

## Keywords

- DISPLACEMENT_FIELD

- D_FILTER

- END_FRAME

- INTENSITIES_FILE_NAME

- INTENSITY

- INTENSITY_LIST

- POLARISATION

- START_FRAME

## Keyword descriptions

DISPLACEMENT_FIELD: logical = F

  Lone keyword: `T`

  Usage: DISPLACEMENT_FIELD T

  References: Stengel2009

  Use the displacement field formulation. [Edit on GitHub]

D_FILTER: real[3] = 1.00000000E+000 1.00000000E+000 1.00000000E+000

  Usage: D_FILTER 1.0 0.0 0.0

  Filter for displacement field (x,y,z-direction) [Edit on GitHub]

END_FRAME: integer = -1

  Usage: END_FRAME -1

  Last frame the field is applied. If an end frame is specified, the number of active frames must be a multiple of the number of the given intensity values. (-1: no end) Attention: ignored for eeq [Edit on GitHub]

INTENSITIES_FILE_NAME: string

  Usage: INTENSITIES_FILE_NAME filename

  File containting a list of intensities, one per line, in a.u. They are applied sequentially, one per frame. If the number of frames exceeds the number of values, the list is cyclically repeated. Attention: not implemented for eeq. [Edit on GitHub]

INTENSITY: real = 0.00000000E+000

  Usage: INTENSITY 0.001

  Intensity of the electric field in a.u, not allowed together with INTENSITY_LIST [Edit on GitHub]

INTENSITY_LIST: real[ ] = 0.00000000E+000

  Usage: INTENSITY_LIST {real} {real} .. {real}

  Intensities of the electric field in a.u. They are applied sequentially, one per frame. If the number of frames exceeds the number of values, the list is cyclically repeated. Attention: not implemented for eeq. [Edit on GitHub]

POLARISATION: real[3] = 0.00000000E+000 0.00000000E+000 1.00000000E+000

  Usage: POLARISATION 0.0 0.0 1.0

  Polarisation vector of electric field [Edit on GitHub]

START_FRAME: integer = 0

  Usage: START_FRAME 0

  First frame the field is applied. (0: first frame) Attention: ignored for eeq [Edit on GitHub]