Description Usage Arguments Details Value References See Also Examples
Get fractional coordinates, neutron scattering length and X-ray scattering factor.
1 2 3 4 5 |
name |
name of chemical element; see details. |
.
scatterFactor |
list containing scattering factor parameters as returned by |
.
Q |
numeric vector containing grid points at which scattering factor should be calculated. |
.
getScatterLength
contains data for neutron scattering lengths of the elements and their isotopes taken from http://www.ncnr.nist.gov/resources/n-lengths/list.html. Parameter name
should be given as in the corresponding table.
getScatterFactor
contains data for X-ray scattering factors of the elements and their isotopes taken from Waasmaier et al., 1995. Parameter name
should be given as in table 1. The atomic scattering factor is calculated using the method developed by Waasmaier et al. that implies approximation by a function
f(s)=a_1 * exp(-b_1 s) + a_2 * exp(-b_2 s) + a_3 * exp(-b_3 s) + a_4 * exp(-b_4 s) + c
, with s = (\frac{Q}{4π})^2.
getBase()
function contains information about fractional coordinates for certain simple structure. Parameter name
can be:
"Cu" to specify fractional coordinates of atoms in monoatomic fcc lattice,
"Fe" to specify fractional coordinates of atoms in monoatomic bcc lattice,
"Na" to specify fractional coordinates of Na atoms in NaCl rock salt structure,
"Cl" to specify fractional coordinates of Cl atoms in NaCl rock salt structure,
"Ca" to specify fractional coordinates of Ca atoms in CaTiO3 ideal perovskite structure,
"Ti" to specify fractional coordinates of Ti atoms in CaTiO3 ideal perovskite structure,
"O3" to specify fractional coordinates of O atoms in CaTiO3 ideal perovskite structure,
"Mg" to specify fractional coordinates of atoms in monoatomic hcp lattice,
"Zn" to specify fractional coordinates of Zn atoms in ZnS wurtzite structure,
"S" to specify fractional coordinates of S atoms in ZnS wurtzite structure.
getBase
: numeric matrix in which each row represents fractional coordinates of the corresponding atom within the primitive cell.
getScatterLength
: numeric describing neutron scattering length for the given element.
getScatterFactor
: list containing X-ray scattering factor parameters for the given element.
scatterFactor
: numeric vector containing scattering factor value(s).
Waasmaier D. and Kirfel A. (1995): New analytical scattering-factor functions for free atoms and ions. Acta Cryst. A51, 416–431.
1 2 3 4 5 6 7 8 9 10 11 12 13 | ## get fractional coordinates for Zn
Cd_base <- getBase("Zn")
## get scattering parameters for Cd
Cd_scL <- getScatterLength("Cd")
Cd_scF <- getScatterFactor("Cd")
Se_base <- getBase("S")
Se_scL <- getScatterLength("Se")
Se_scF <- getScatterFactor("Se")
Q <- seq(0.1, 15, 0.1)
## plot scattering factor
plot(Q, scatterFactor(Se_scF, Q))
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