I don't think the atom bomb was what sealed the deal. I don't think the Japanese leadership fully understood what they were even facing. While I'm not an expert on WWII I do think that it's accurate to say lots of scholars feel that way and that the idea has gained a lot of traction. Still, it's not something I'm trying to pick a fight over, just pointing out that it's very complex issue. I think it's pretty clear that Japan never believed it could win a war with the US in the first place; rather they felt the American people had no appetite for war and could forced into settlement if hit hard at the outset.