  Using the coupled cluster method we study the phase diagram of the spin-1/2
Heisenberg antiferromagnet on a honeycomb lattice with nearest-neighbor
exchange coupling $J_{1}>0$ and frustrating next-nearest-neighbor coupling
$J_{2} \equiv xJ_{1}>0$. In the range $0<x<1$ we find four phases exhibiting
respectively N\'{e}el, 6-spin plaquette, staggered dimer, and N\'{e}el-II
orderings, with quantum critical points at $x_{c_{1}} \approx 0.207(3),
x_{c_{2}} \approx 0.385(10)$, and $x_{c_{3}} \approx 0.65(5)$. The transitions
at $x_{c_{1}}$ and $x_{c_{3}}$ appear to be continuous (and hence deconfined)
ones, while that at $x_{c_{2}}$ appears to be a direct first-order one.
