GrSAS: Functions to calculate the gamma baseline term for PDF

Description Usage Arguments Details Value References See Also Examples

Description

Functions to calculate analytically the gamma baseline term given a particle lattice and size parameters.

Usage

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GrSAS(r, Rcore=NA, Rpart, latticep, latticepShell=NA, 
    N1, N2=NA, sym, symShell=NA)   
GrSASCS(r, Rcore=NA, Rpart, latticep, latticepShell=NA, 
    N1, N2=NA, sym, symShell=NA)

Arguments

r

numeric vector that contains grid points at which baseline term should be evaluated.

Rcore

numeric which, if not NA, determines the radius (radii) of the core.

Rpart

numeric indicating the radius (radii) of the particle.

latticep, latticepShell

numeric vectors indicating the lattice parameter(s) for the core( shell); see simPart for details.

N1, N2

numeric indicating number of atoms within the unit cell in the particle core (shell).

sym, symShell

characters describing the structure to be used in the particle core (shell) simulations; see simPart.

Details

Function GrSAS can be used for both uniform and core/shell particles. In the second case the uniform model is applied with scattering length density averaged through the nanoparticle. Function GrSASCS calculates baseline term for core/shell particles using model described in Glatter, 1979.

Value

numeric vector of function values.

References

Glatter O. (1979): The interpretation of real-space information from small-angle scattering experiments. J. Appl. Cryst., 12, 166–175.

See Also

calcPDF, calcQDepPDF

Examples

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## calculate baseline term for uniform particle			
gammaR <- GrSAS(r=seq(0.01, 30, 0.01), Rpart=15, 
    latticep=c(4.3, 7.02), sym="hcp", N1=4)
plot(seq(0.01, 30, 0.01), gammaR, type="l")

## compare with baseline computed as Fourier transform 
## of the total scattering function:
Zn <- createAtom("Zn")
S <- createAtom("S")
part <- simPart(atoms=list(Zn,S), r=15, latticep=c(4.3, 7.02), 
    sym="hcp")
gQSAS <- calcTotalScatt(part, type="neutron",  minQ=0.001, 
    maxQ=0.9, dQ=0.005)
gammaR2 <- calcQDepPDF(part, minR=0.01, maxR=30, dr=0.01, 
    maxQ=.85, minQ=0.001, verbose=20,
    preTotalScat=list(Q=gQSAS$Q, gQ=gQSAS$gQ))
lines(gammaR2$r, gammaR2$gr, col=2)


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