# MULTIPOLES

References: Aguado2003, Laino2008

Enables the use of multipoles in the treatment of the electrostatics. [Edit on GitHub]

## Keywords

- SECTION_PARAMETERS

- EPS_POL

- MAX_IPOL_ITER

- MAX_MULTIPOLE_EXPANSION

- POL_SCF

## Keyword descriptions

SECTION_PARAMETERS: logical = F

  Lone keyword: `T`

  Usage: &MULTIPOLES T

  Controls the activation of the Multipoles [Edit on GitHub]

EPS_POL: real = 5.00000000E-008

  Usage: EPS_POL {real}

  Specify the rmsd threshold for the derivatives of the energy towards the Cartesian dipoles components [Edit on GitHub]

MAX_IPOL_ITER: integer = 0

  Usage: MAX_IPOL_ITER {int}

  Specify the maximum number of iterations for induced dipoles [Edit on GitHub]

MAX_MULTIPOLE_EXPANSION: enum

  Usage: MAX_MULTIPOLE_EXPANSION DIPOLE

  Valid values:

  - `NONE` No multipolar terms! Check the codes providing a zero contribution.

  - `CHARGE` Use up to the Charge term

  - `DIPOLE` Use up to the Dipole term

  - `QUADRUPOLE` Use up to the Quadrupole term

  Specify the maximum level of multipoles expansion used for the electrostatics. [Edit on GitHub]

POL_SCF: enum = NONE

  Usage: POL_SCF CONJUGATE_GRADIENT

  Valid values:

  - `NONE` No inducible multipoles.

  - `SELF_CONSISTENT` Conventional self-consistent iteration.

  - `CONJUGATE_GRADIENT` Linear conjugate-gradient optimization of the sum of the electrostatic and induction energy. This method does not support non-linear polarization but is sometimes faster.

  Specify the method to obtain self consistent induced multipole moments. [Edit on GitHub]