The Coen brothers have made several good films with sociopaths/psychopaths.
The Peter Stormare character in
Fargo is a pretty good psychopath character. Not brilliant, just a human being with no moral compass.
More towards what you are looking for is Anton Chigurh from
No Country For Old Men.
Just look at this:
I think to get a good grasp of the sociopath you have to approach the rest of humanity with a complete disregard to other people as human beings. A friendly smile is only an invitation to utility, the entire history of somebody you have known for years is only useful because you it lets you know how you will be able to use that person to accomplish your own aims.
I should say, the brilliant sociopath is usually my least favorite character in any movie, but only because it's often so incompetently done.
You don't really need a film example, just get rid of all humanity and warmth towards the people you know. Psychopaths don't succeed because they're brilliant, although many of them are. They succeed because they do not care about other people at all. Once you free yourself of caring the world is your oyster.