@article {6,
	title = {Ab-initio theory of polar semiconductor surfaces: II.(2 x 2) reconstructions and related transitions on GaAs(111)},
	journal = {Phys. Rev. B},
	volume = {35},
	year = {1987},
	pages = {9636},
	author = {E. Kaxiras and Y. Bar-Yam and J.D. Joannopoulos and K.C. Pandey}
}
