Print screen, copy and paste

Is there a function for doing a print screen? Exactly like the key on your keyboard. So I could have a script that copy’s what’s on the screen (or possibly a selected area of the screen) into the buffer (or whatever it’s called). So that it could be pasted into photoshop (manually, later on).

It has to be done this way too, my goal doesn’t involve getting screen grabs saved as images. It has to go through the print screen method.

I found the Application.CaptureScreenshot function. It seems to be only for saving images. Is there a way to make it store that image in the buffer instead? Even if it overwrote it with every update?