sw_mff

Syntax

[~, coeff, s] = sw_mff(atomname)

[formfactval, coeff, s] = sw_mff(atomname,Q)

Description

[~, coeff, s] = sw_mff(atomname) returns the magnetic form factor coefficients for the magnetic atom identified by a string, e.g. 'MCR3'. The function reads the magion.dat file for the stored form factor coefficients.

[formfactval, coeff, s] = sw_mff(atomname,Q) also calculates the form factor values at the given $Q$ points (in Å$^{-1}$ units.

The source of the form factor data are:

1. A.-J. Dianoux and G. Lander, Neutron Data Booklet (2003).
2. K. Kobayashi, T. Nagao, and M. Ito, Acta Crystallogr. A. 67, 473 (2011).

Input Arguments

atomName

String, contains the name of the magnetic ion in FullProf notation (e.g. for Cr$$^{3+} use 'MCR3' or 'Cr3'). It can be also a vector of the 7 form factor coefficients. If the string contains whitespace, the first word will be used as input. Can be also a cell of strings to calculate coefficients for multiple ions.

Q

Momentum transfer in Å$^{-1}$ units in a matrix with dimensions of $[1\times n_Q]$ or $[3\times n_Q]$.

Output Arguments

formFactVal

Value of the form factor, evaluated at the given $Q$ points.

coeff

Form factor coefficients according to the following formula: $$\langle j_0(Q_s)\rangle = A\exp(-a\cdot Q_s^2) + B\exp(-b\cdot Q_s^2) + C\exp(-c\cdot Q_s^2) + D\exp(-d\cdot Q_s^2) + E$$

where $Q_s = \frac{Q}{4\pi}$ and $A$, $a$, $B$, … are the coefficients. The $D$ and $d$ coefficients can be zero.

S

Value of the spin quantum number (read from the spin column in magion.dat).