Are there any accidents (philosophical term) in God? Accident being defined as an attribute or property contingent upon the existence of something else, from the Latin word accidēns, or the Greek word συμβεβηκός (symbebēkos). Do accidents exist in God?
St. Thomas Aquinas addresses this directly in the Summa.

Article 6. Whether in God there are any accidents?


  I answer that, From all we have said, it is clear there can be no
  accident in God.
  
  First, because a subject is compared to its accidents as potentiality
  to actuality; for a subject is in some sense made actual by its
  accidents. But there can be no potentiality in God, as was shown (2,
  3).
  
  Secondly, because God is His own existence; and as Boethius says
  (Hebdom.), although every essence may have something superadded to it,
  this cannot apply to absolute being: thus a heated substance can have
  something extraneous to heat added to it, as whiteness, nevertheless
  absolute heat can have nothing else than heat.
  
  Thirdly, because what is essential is prior to what is accidental.
  Whence as God is absolute primal being, there can be in Him nothing
  accidental. Neither can He have any essential accidents (as the
  capability of laughing is an essential accident of man), because such
  accidents are caused by the constituent principles of the subject. Now
  there can be nothing caused in God, since He is the first cause. Hence
  it follows that there is no accident in God.


Briefly, there are no accidents in God.

The entire section on The Simplicity of God may help to clarify this, if there's any confusion. The main contributing points, I think, are that God's essence and existence are one in the same, that God is His own essence and existence, and that God is absolutely simple.