disunite vs split up

disunite

verb
  • To disintegrate; to come apart. 

  • To cause disagreement or alienation among or within. 

  • To separate, sever, or split. 

split up

verb
  • separate, disassociate, cause to come apart. 

  • Cease to be together, break apart from the group. 

adj
  • Divided or separated. 

How often have the words disunite and split up occurred in a corpus of books? (source: Google Ngram Viewer )