Considering the Bomb, dropping it had much more to do with showing some 300 well lead, experienced and perfectly equiped Russian divisions that they shoudl reconsider the Holiday plans on the Cote Azur.
if you're referring to the Hokkaido landing, you would be correct that it was a benefit. But it was far secondary to ending the war with Japan, as the top historians agree.
I am referring to Operation Augst Storm (Soviet Invasion of Manchuria), in which a Japanese force on 1 million soldiers ceased to exist in a matter of roughly 2 weeks.
A US source on the affair:
Leavenworth Papers No. 7 (August Storm: The Soviet 1945 Strategic Offensive in Manchuria)
Also, the Soviets held a clear conventional superiority along the "iron curtain", which actually prompted Churchill to keep captured German units "ready" for a clash with the SU, in direct violation of a number of allied agreements, and in a ridiculous show of bad faith.
Given that August Storm was bound to happen (it was agreed beforehand that the USSR would open a northern front 3 months after Germanys surrender), the Bomb had 2 main goals:
1: Make sure Japan surrender to the US, not to the USSR¨
The Japanese could guess that the western alllies would be a bit pissed concerning Japanese war crimes, however, Japanese crimes against Russian were much more limited, so they could have considered a surrender to the USSR in order to prevent persecution.
2: Show the USSR that their conventional superiority can be countered.