"While the true extent and nature of Manhattan's power is not known, here is a list of some of the powers, abilities, and traits that he has exhibited:
Size Alteration
Enhanced Strength
Teleportation of himself or other individuals over incredible distances
Matter Manipulation/Atomic Structure Control – limits unknown. Has been shown to be able to do things like: create crystalline structures on Mars, create a small amount of water, melt a portion of a tank. It was also stated he possibly could have turned a gun to steam, bullets to mercury, and a bottle to snowflakes by an angry Blake, though he is never actually shown doing these things.
Can create copies of himself which act independently of each other, but operate in an intelligent collective fashion.
Intangibility
Atemporal (in terms of his perception of time).
Does not appear to age.
Does not seem to require food, water, or air.
Creation of Environmental Fields – as seen when he creates a field around Laurie, allowing her to survive on Mars.
Can read atoms and sense tachyons
Telekinesis
Able to restructure himself after the removal of his intrinsic field.
Disintegration/Intrinsic Field removal – It is unclear whether he is disintegrating his targets or removing their intrinsic field. It should be noted that he does seem to need to aim his hand at the intended target."
http://www.comicvine.com/dr-manhattan/4005-40527/