\documentclass{standalone}
\usepackage{tikz}
\usepackage{graphene}
\begin{document}
\begin{tikzpicture}

% draw grids
\graphene{(0,0)}{}
\graphene{(-1,0)}{dashed}

% bounding box
\path\mlo++\mlo++(-0.1,-0.1)coordinate(A);
\path\lt++(-60:1)++(0.1,-0.1)coordinate(B);
\path\lo++\mlt++\lo++(60:1)++(0.1,0.1)coordinate(C);
\path\mlt++\mlt++\lo++\mlt++(-0.1,0.1)coordinate(D);

\sitelattice{at}{(-1,0)}{}
\sitelattice{bt}{(-1,0)}{color=green}
\sitelattice{a}{(0,0)}{color=green}
\sitelattice{b}{(0,0)}{}



\end{tikzpicture}
\end{document}