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Linear scaling computation of the Fock matrix. VIII. Periodic boundaries for exact exchange at the $Γ$-point

A translationally invariant formulation of the Hartree-Fock (HF) $Γ$-point approximation is presented. This formulation is achieved through introduction of the Minimum Image Convention (MIC) at the level of primitive two-electron integrals, and implemented in a periodic version of the ONX algorithm [J. Chem. Phys, {\bf 106} 9708 (1997)] for linear scaling computation of the exchange matrix. Convergence of the HF-MIC $Γ$-point model to the HF ${\bf k}$-space limit is demonstrated for fully periodic magnesium oxide, ice and diamond. Computation of the diamond lattice constant using the HF-MIC model together with the hybrid PBE0 density functional [Theochem, {\bf 493} 145 (1999)] yields $a_0=3.569$Åwith the 6-21G* basis set and a $3\times3\times3$ supercell. Linear scaling computation of the HF-MIC exchange matrix is demonstrated for diamond and ice in the condensed phase