### Syntax

aList = sw_extendlattice(nExt,aList)

[aList, SSext] = sw_extendlattice(nExt,aList,SS)

### Description

aList = sw_extendlattice(nExt,aList) creates a superlattice and calculates all atomic positions within the new superlattice by tiling it with the original cell.

[aList, SSext] = sw_extendlattice(nExt,aList,SS) also calculates the bond matrix for the supercell by properly including all internal bonds and bonds between atoms in different supercells.

### Input Arguments

nExt
Size of the supercell in units of the original cell in a row vector with 3 elements.
aList
List of the atoms, produced by spinw.matom.
SS
Interactions matrices in the unit cell. Struct where each field contains an interaction matrix.

### Output Arguments

aList
Parameters of the magnetic atoms in a struct with the following fields:
• RRext Positions of magnetic atoms in lattice units of the supercell stored in a matrix with dimensions of $$[3\times n_{magExt}]$$.
• Sext Spin length of the magnetic atoms in a row vector with $$n_{magExt}$$ number of elements.
SSext
Interaction matrix in the extended unit cell, struct type. In the struct every field is a matrix. Every column of the matrices describes a single bond, the following fields are generally defined:
• iso Isotropic exchange interactions.
• ani Anisotropic exchange interations.
• dm Dzyaloshinsky-Moriya interaction terms.
• gen General $$[3\times 3]$$ matrix contains the exchange interaction.