Example single ion property file for a simple antiferromagnet

Here is an example file mcphas.cf1 describing the anisotropy of a simple antiferromagnet with Ce atoms having basal plane anisotropy. Note the axis convention xyz$\vert\vert$abc, in case of non-orthogonal axes the convention is $y\vert\vert\vec b$, $z\vert\vert(\vec a \times \vec b)$ and $x$ perpendicular to $y$ and $z$.

#!MODULE=so1ion
#<!--mcphase.sipf-->
#***************************************************************
# Single Ion Parameter File for Module Cfield for  
# mcphas version 3.0
# - program to calculate static magnetic properties
# reference: M. Rotter JMMM 272-276 (2004) 481
# mcdisp version 3.0
# - program to calculate the dispersion of magnetic excitations
# reference: M. Rotter et al. J. Appl. Phys. A74 (2002) 5751
# mcdiff version 3.0
# - program to calculate neutron and magnetic xray diffraction
# reference: M. Rotter and A. Boothroyd PRB 79 (2009) 140405R
#***************************************************************
#
#
# crystal field paramerized in Stevens formalism
#
#-----------
IONTYPE=Ce3+
#-----------

#--------------------------------------------------------------------------
# Crystal Field parameters in Stevens Notation (coordinate system xyz||abc)
#--------------------------------------------------------------------------
units=meV
B20=0.02


#----------------
# Stevens Factors
#----------------
ALPHA=-0.0571429
BETA=0.00634921
GAMMA=0

#---------------------------------------------------------
# Radial Matrix Elements (e.g. Abragam Bleaney 1971 p 399)
#---------------------------------------------------------
#<r^2> in units of a0^2 a0=0.5292 Angstroem
R2=1.309
#<r^4> in units of a0^4 a0=0.5292 Angstroem
R4=3.964
#<r^6> in units of a0^6 a0=0.5292 Angstroem
R6=23.31

#----------------
# Lande factor gJ
#----------------
GJ=0.857143

#-------------------------------------------------------
# Neutron Scattering Length (10^-12 cm) (can be complex)
#-------------------------------------------------------
SCATTERINGLENGTHREAL=0.484
SCATTERINGLENGTHIMAG=0
#  ... note: - if an occupancy other than 1.0 is needed, just reduce 
#              the scattering length linear accordingly

#-------------------------------------------------------
# Debye-Waller Factor: sqr(Intensity)~|sf|~EXP(-2 * DWF *s*s)=EXP (-W)
#                      with s=sin(theta)/lambda=Q/4pi
# relation to other notations: 2*DWF=Biso=8 pi^2 <u^2>
# unit of DWF is [A^2]
#-------------------------------------------------------
DWF=0
#--------------------------------------------------------------------------------------
# Neutron Magnetic Form Factor coefficients - thanks to J Brown
#   d = 2*pi/Q      
#   s = 1/2/d = Q/4/pi   
#   sin(theta) = lambda * s
#   r= s*s = Q*Q/16/pi/pi
#
#   <j0(Qr)>=   FFj0A*EXP(-FFj0a*r) + FFj0B*EXP(-FFj0b*r) + FFj0C*EXP(-FFj0c*r) + FFj0D
#   <j2(Qr)>=r*(FFj2A*EXP(-FFj2a*r) + FFj2B*EXP(-FFj2b*r) + FFj2C*EXP(-FFj2c*r) + FFj2D
#   <j4(Qr)>=r*(FFj4A*EXP(-FFj4a*r) + FFj4B*EXP(-FFj4b*r) + FFj4C*EXP(-FFj4c*r) + FFj4D
#   <j6(Qr)>=r*(FFj6A*EXP(-FFj6a*r) + FFj6B*EXP(-FFj6b*r) + FFj6C*EXP(-FFj6c*r) + FFj6D
#
#   Dipole Approximation for Neutron Magnetic Formfactor:
#        -Spin Form Factor       FS(Q)=<j0(Q)>
#        -Angular Form Factor    FL(Q)=<j0(Q)>+<j2(Q)>
#        -Rare Earth Form Factor F(Q) =<j0(Q)>+<j2(Q)>*(2/gJ-1)

#--------------------------------------------------------------------------------------
FFj0A=+0.2953 FFj0a=+17.6846 FFj0B=+0.2923 FFj0b=+6.7329 FFj0C=+0.4313 FFj0c=+5.3827 FFj0D=-0.0194
FFj2A=+0.9809 FFj2a=+18.0630 FFj2B=+1.8413 FFj2b=+7.7688 FFj2C=+0.9905 FFj2c=+2.8452 FFj2D=+0.0120



Martin Rotter 2017-01-10