Charge-constrained auxiliary-density-matrix methods for the Hartree-Fock exchange contribution

Three new variants of the auxiliary-density-matrix method (ADMM) of Guidon, Hutter, and Vande-Vondele [J. Chem. Theory Comput. 6, 2348 (2010)] are presented with the common feature that they have a simplified constraint compared with the full orthonormality requirement of the earlier ADMM1 method. All ADMM variants are tested for accuracy and performance in all-electron B3LYP calculations with several commonly used basis sets. The effect of the choice of the exchange functional for the ADMM exchange-correction term is also investigated. (C) 2014 AIP Publishing LLC.