spinw.addatom method#

Syntax#

addatom(obj,Name,Value)

Description#

addatom(obj,Name,Value) adds a new atom to the list of symmetry inequivalent sites together with its properties, such as position, spin quantum number, form factor, etc.

Examples#

To add a magnetic atom with \(S=1\) at position \(r=(0,0,0)\) and a non-magnetic one at \(r=(1/2,0,0)\) with red and blue color respectively use the following command

crystal = spinw;
crystal.genlattice('lat_const',[4 3 3])
crystal.addatom('r',[0 1/2; 0 0; 0 0],'S',[1 0],'color',{'red' 'blue'})
crystal.plot

Input Arguments#

obj: spinw object.

Name-Value Pair Arguments#

r: Atomic positions stored in a matrix with dimensions of \([3\times n_{atom}]\).
label: Names of the atoms in a cell for plotting and form factor calculations (see magion.dat), e.g. label={'atom1' 'atom2' 'atom3'}. Default value is atomi, where i is the atom index.
S: Spin quantum number stored in a row vector with \(n_{atom}\) elements, for non-magnetic atoms set S to zero. If not given the spin quantum number is guessed from the given label of the atom. For example if label is MCr3+ or Cr3+ then the \(S=3/2\) high spin state is assumed for Cr\(^{3+}\). The spin values for every ion is stored in the magion.dat file. If the atom type is unknown \(S=0\) is assumed.
color: RGB color of the atoms for plotting stored in a matrix with dimensions of \([3\times n_{atom}]\), where each column describes an RGB color. Each value is between 0 and 255. Default value is the color stored in the atom.dat file. Alternatively a name of the color can be given as a string, for example 'White', for multiple atoms package it into a cell. For the list of colors, see swplot.color or the color.dat file.
ox: Oxidation number given as a double or it will be determined automatically from label. Default value is 0.
occ: Occupancy, given as double. Default value is 1.
formfact: Neutron scattering form factor, given as a row vector with 9 numbers, for details see sw_mff. Also string labels can be used from the magion.dat file.
formfactn: Same as the formfact option.
formfactx: X-ray scattering form factor, given as 9 numbers, for details see sw_cff, also labels can be used from the xrayion.dat file.
Z: Atomic number, given as integer or determined from the atom label automatically. Default value is 113 (Unobtanium).
A: Atomic mass, given as integer. Default is -1 for the natural mixture of isotopes.
bn: Neutron scattering length, given as double. Not implemented yet.
bx: X-ray scattering length.
biso: Isotropic displacement factors in units of Å\(^2\). 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 \(exp(-2W(d))\).
update: If true, existing atom with the same label and position as a new one will be updated. Default is true.

Output Arguments#

The function modifies the spinw.unit_cell property of the obj spinw object.