The Collaborative International Dictionary of English v.0.48:

Psychotherapeutics \Psy`cho*ther`a*peu"tics\, n. [Psycho- +
   therapeutics.] (Med.)
   The treatment of disease by acting on the mind, as by
   suggestion; mind cure; psychotherapy.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

psychotherapeutics
    n 1: the branch of psychiatry concerned with psychological
         methods [syn: psychotherapy, psychotherapeutics,
         mental hygiene]