atom_gauss {crone}

Gaussian atom

Description

Gaussian atom

Usage

atom_gauss(x, a, x0 = 0, Z = 1, B = 0, k = ksigma)

Arguments

x

Point in the 1D cell at which this function is calculated.

a

A real number. The width of the unit cell in which the gaussian atom is placed.

x0

A real number. The point corresponding to the atom's peak.

Z

An integer number. Z is the atomic number of the atom (Z(H)=1, Z(He)=2,Z(Li)=3,Z(B)=4, etc).

B

A real number. This is the B factor characterizing the atom's thermal agitation. It is given as B=8*pi^2*U, where U is the variance of the position of the atoms' nucleus around the equilibrium position.

k

A real number. It controls the standard deviation of the gaussian function describing the atom and, thus, the shape of the associated peak. The standard deviation sigma is given by: sigma = k * sqrt(Z)

Value

A vector of length equal to the length of vector x, with values equal to the evaluated gaussian atom.

Examples

# Carbon gaussian atom in the middle of a cell
a <- 10
x0 <- 5
Z <- 6
x <- seq(0,a,length=1000)
rho <- atom_gauss(x,a,x0,Z)
plot(x,rho,type="l",xlab="x",ylab=expression(rho))