Source : Webster's Revised Unabridged Dictionary (1913)

Schismatical \Schis*mat"ic*al\, a.
   Same as {Schismatic}. -- {Schis*mat"ic*al*ly}, adv. --
   {Schis*mat"ic*al*ness}, n.

Source : WordNet®

schismatically
     adv : in a manner that is schismatic