deletions | additions       diff --git a/Delta_sigma_i__RC_is__.tex b/Delta_sigma_i__RC_is__.tex  index 075160d..9b9f6f3 100644  --- a/Delta_sigma_i__RC_is__.tex  +++ b/Delta_sigma_i__RC_is__.tex 
...
$\Delta \sigma^i_{RC}$ is the effect of ring current on the chemical shielding. Usually this is only significant for proton shift and is thus only calculated for the H$\alpha$ and amide protons. The ring current is calculated by a simple point-dipole model equation   $$\Delta \sigma^i_{RC}=iB\frac{1-3 \cos^2(\theta)}{r^3} $$  The model depends on two the  parameters $i$ and $B$ $i$, which is the side-chain-specific ring-current intensity relative to benzene, $B$, which is a constant in the model,  and the vector $\mathbf{r}$, which is the vector from the proton to the center of the aromatic ring. $\theta$ is the angle between $\mathbf{r}$ and the vector normal to the aromatic ring system. The cut-off for calculating ring current is 8 Å in Procs15 and the value for $i$ and $B$ are taken from \cite{Christensen_2011}.