# Two Lorentzian

## Description:

Definition

The scattering intensity $I(q)$ is calculated as

$$I(q) = \frac{A}{1 +(Q\xi_1)^n} + \frac{C}{1 +(Q\xi_2)^m} + \text{B}$$
where $A$ = Lorentzian scale factor #1, $C$ = Lorentzian scale #2, $\xi_1$ and $\xi_2$ are the corresponding correlation lengths, and $n$ and $m$ are the respective power law exponents (set $n = m = 2$ for Ornstein-Zernicke behaviour).

For 2D data the scattering intensity is calculated in the same way as 1D, where the $q$ vector is defined as

$$q = \sqrt{q_x^2 + q_y^2}$$

References

None.

Authorship and Verification

**Author:** NIST IGOR/DANSE **Date:** pre 2010