The first thing to pay attention to is that the notation like (4,0) is not well-defined for GNRs, so it can easily mean different things in different codes. However, in ATK, if you enter n=4 and m=0 in the GNR builder, you will obtain what corresponds to a (4,0) nanotube, unfolded. This is actually an armchair edge ribbon (the nanotube (4,0) is however of zigzag type), and if you run any calculation with ATK on it you will find that it is indeed semiconducting.
PS: This post belongs in Questions, not News and Announcements
PS2: Don't make polls unless you are asking the community a question you want them to vote on.