let’s name a few “peaceful” atheists- Hitler, Lenin, Stalin, Mao, Castro
I usually leave out Hitler in such lists as he did espouse some sort of faith. He called it Christianity but of course he was no Christian. Instead of Hitler, use Stalin, who was most definitely a card-carrying atheist.
As for morals, these atheists seem to like to borrow those which come from a Judeo-Christian worldview. Applied consistently, they will make someone successful (though I've seen numerous personal examples with all the atheists I know which can shoot down every point listed in the article about how atheists are supposedly "better" than those of faith).
The problem is though, that for atheism, by definition all morals are relative to the person. One atheist might think that behaving towards others in Judeo-Christian way is right and good, and another, such as the ones you listed, would think that being a murderous tyrant towards others is also right and good.
To put it another way, if I was an atheist, and I saw someone who had something I wanted, why would it be wrong in a moral (not legal) sense for me to kill that person and steal that item? From a Christian perspective, I could say that God commands me not to do that, and He will execute judgement on me if I do it.