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).