# pair_style spin/exchange command

## Syntax

pair_style spin/exchange cutoff

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

## Examples

pair_style spin/exchange 4.0
pair_coeff * * exchange 4.0 0.0446928 0.003496 1.4885
pair_coeff 1 2 exchange 6.0 -0.01575 0.0 1.965


## Description

Style spin/exchange computes the exchange interaction between pairs of magnetic spins:

where si and sj are two neighboring magnetic spins of two particles, rij = ri - rj is the inter-atomic distance between the two particles, and J(rij) is a function defining the intensity and the sign of the exchange interaction.

This function is defined as:

where a, b and d are the three constant coefficients defined in the associated “pair_coeff” command.

The coefficients a, b, and d need to be fitted so that the function above matches with the value of the exchange interaction for the N neighbor shells taken into account.