Full Idea
Xenophon indirectly indicates that he does not associate Socrates in any way with the tripartite psychology of the 'Republic', for within that theory akrasia would be all too possible.
Gist of Idea
Socrates did not accept the tripartite soul (which permits akrasia)
Source
comment on Socrates (reports of career [c.420 BCE]) by Gregory Vlastos - Socrates: Ironist and Moral Philosopher p.102
Book Reference
Vlastos,Gregory: 'Socrates: Ironist and Moral Philosopher' [CUP 1992], p.102