# pair_style spin/magelec command

## Syntax

pair_style spin/magelec cutoff

• cutoff = global cutoff pair (distance in metal units)

## Examples

pair_style spin/magelec 4.5
pair_coeff * * magelec 4.5 0.00109 1.0 1.0 1.0


## Description

Style spin/me computes a magneto-electric interaction between pairs of magnetic spins. According to the derivation reported in (Katsura), this interaction is defined as:

where si and sj are neighboring magnetic spins of two particles, eij = (ri - rj)/|ri-rj| is the normalized separation vector between the two particles, and E is an electric polarization vector. The norm and direction of E are giving the intensity and the direction of a screened dielectric atomic polarization (in eV).

From this magneto-electric interaction, each spin i will be submitted to a magnetic torque omega, and its associated atom can be submitted to a force F for spin-lattice calculations (see fix_nve_spin), such as:

with h the Planck constant (in metal units).

More details about the derivation of these torques/forces are reported in (Tranchida).

## Restrictions

All the pair/spin styles are part of the SPIN package. These styles are only enabled if LAMMPS was built with this package, and if the atom_style “spin” was declared. See the Build package doc page for more info.