Properties#

The spinw object properties store all the information necessary for the spin wave calculation. It has 8 fields with several subfields, see below.

lattice#

stores the unit cell parameters

lat_const
Lattice constants in a \([1\times 3]\) vector in units defined in [spinw.unit] (default value is \ang).
angle
[\\alpha,\\beta,\\gamma] angles in a \([1\times 3]\) vector in radian units.
sym
Symmetry operators stored in matrix with dimensions of \([3\times 4 \times n_{op}]\).
origin
Origin of the cell in lattice units.
label
Label of the space group.

Stores the atoms in the crystallographic unit cell

r
Positions of the atoms in the unit cell, stored in a matrix with dimensions of \([3\times n_{atom}]\), values are in lattice units.
S
Spin quantum number of the atoms, stored in a row vector with \(n_{atom}\) number of elements, non-magnetic atoms have S=0.
label
Label of the atom, strings stored in a \([1\times n_{atom}]\) cell.
color
Color of the atom stored in a matrix with dimensions of \([3\times n_{atom}]\), where every column defines an RGB color with values between 0 and 255.
ox
Oxidation number of the atom, stored in a \([1\times n_{atom}]\) matrix.
occ
Site occupancy in a \([1\times n_{atom}]\) matrix.
b
Scattering length of the atoms for neutron and x-ray stored in a \([2\times n_{atom}]\) matrix, first row is neutron, second row is for x-ray.
ff
Form factor of the site stored in a \([2\times 9\times n_{atom}]\) matrix, first row is the magnetic form factor for neutrons, the second row is the charge form factor for x-ray cross section.
Z
Atomic number in a row vector.
A
Atomic mass (N+Z) for isotopes and -1 for natural distribution of isotopes stored in a row vector.
biso
Isotropic displacement factors in units of \ang\(^2\). Definition is the same as in FullProf, defining the Debye-Waller factor as \(W(d) = 1/8*b_{iso}/d^2\) which is included in the structure factor as \(\exp(-2W(d))\).

stores the crystal twin parameters

rotc
Rotation matrices in the \(xyz\) coordinate system for every twin, stored in a matrix with dimensions of \([3\times 3\times n_{twin}]\).
vol
Volume ratio of the different twins, stored in a row vector with \(n_{twin}\) elements.

stores 3x3 matrices for using them in the Hamiltonian

mat
Stores the actual values of 3x3 matrices, in a matrix with dimensions of \([3\times 3\times n_{matrix}]\), if assigned for a bond, the unit of energy is stored in [spinw.unit] (default value is meV).
color
Color assigned for every matrix, stored in a matrix with dimensions of \([3\times n_{matrix}]\), with each column defining an RGB value.
label
Label for every matrix, stored as string in a cell with dimensions of \([1\times n_{matrix}]\).

stores single ion terms of the Hamiltonian

aniso
Row vector that contains \(n_{magatom}\) integers, each integer assignes one of the matrices from the [spinw.matrix] property to a magnetic atom in the generated [spinw.matom] list as a single ion anisotropy. Zero value of aniso means no single ion anisotropy for the corresponding magnetic atom.
g
Row vector with \(n_{magatom}\) integers, each integer assignes one of the matrices from the [spinw.matrix] property to a magnetic atom in the spinw.matom list as a g-tensor. Zero value of g means a default g-value of 2 for the corresponding atoms.
field
External magnetic field stored in a row vector with 3 elements, unit is defined in [spinw.unit] (default unit is Tesla).
T
Temperature, scalar, unit is defined in [spinw.unit] (default unit is Kelvin).

stores the list of bonds

dl
Distance between the unit cells of two interacting spins, stored in a \([3\times n_{coupling}]\) matrix.
atom1
First magnetic atom, pointing to the list of magnetic atoms in the list generated by spinw.matom, stored in a row vector with \(n_{coupling}\) element.
atom2
Second magnetic atom, same as atom1.
mat_idx
Stores pointers to matrices for every coupling in a \([3\times n_{coupling}]\) matrix, maximum three matrix per coupling (zeros for no coupling) is allowed.
idx
Neighbor index, increasing indices for the equivalent couplings, starting with 1,2,… which means first and second neighbor bonds, respectively.
type
Type of coupling corresponding to mat_idx matrices. Default is 0 for quadratic exchange, type = 1 for biquadratic exchange.
sym
If true the bond symmetry operators will be applied on the assigned matrix.
rdip
Maximum distance until the dipolar interaction is calculated. Zero value means no dipolar interactions are considered.
nsym
The largest bond idx value that is generated using the space group operators. Typically very long bonds for dipolar interactions won’t be calculated using space group symmetry.

stores the magnetic structure

F
Complex magnetization (strictly speaking complex spin expectation value) for every spin in the magnetic cell, represented by a matrix with dimensions of \([3\times n_{magext}\times n_k]\), where nMagExt = nMagAtom*prod(N_ext) and \(n_k\) is the number of the magnetic propagation vectors.
k
Magnetic propagation vectors stored in a matrix with dimensions of \([3\times n_k]\).
N_ext
Size of the magnetic supercell in lattice units, default value is [1 1 1] emaning that the magnetic cell is identical to the crystallographic cell. The \([1\times 3]\) vector extends the cell along the \(a\), \(b\) and \(c\) axes.

stores the physical units for the Hamiltonian

Default values are meV, T, \(\unicode{x212B}\) and K for energy, magnetic field, length and temperature, respectively.

kB
Boltzmann constant, default value is 0.0862 meV/K.
muB
Bohr magneton, default values is 0.0579 meV/T.
mu0
Vacuum permeability, default value is 201.335431 T\(^2\unicode{x212B}^3\)/meV.
label
Labels for distance, energy, magnetic field and temperature stored in a cell with dimensions \([1\times 4]\).
nformula
Number of formula units in the unit cell.
qmat
Transformation matrix that converts the given \(Q\) values into the internal reciprocal lattice. The matrix has dimensions of \([3\times 3]\).

stores temporary values

This property should be only used to check consistency of the code.

{% include warning.html content=”Changing these values is strongly discouraged as it can break the code!” %}