# Ambiguity with Kronecker Delta function

Given $$Q = \sum_{i j s r} [(a_{i j s} − \frac{k_{i s} k_{j s}}{2m_{s}}) \delta(s,r) + c_{jsr} \delta(i,j)] \delta(\gamma_{i,s},\gamma_{j, j})$$

Where $$\delta$$ is Kronecker function. I am having problem, with understanding this equation specifically this part $$\delta(\gamma_{i,s},\gamma_{j, j})$$. To be more precise , I know the definition of Kronecker function for $$\delta(i,j)$$ but how this guy, $$\delta(\gamma_{i,s},\gamma_{j, j})$$, behaves?

• It's $1$ if $\gamma_{i,\,s}=\gamma_{j,\,j}$, or $0$ otherwise. – J.G. Apr 4 at 11:32