title: Expanding the Scope of Density Derived Electrostatic and Chemical Charge Partitioning to Thousands of Atoms.
abstract: The density derived electrostatic and chemical (DDEC/c3) method is implemented into the onetep program to compute net atomic charges (NACs), as well as higher-order atomic multipole moments, of molecules, dense solids, nanoclusters, liquids, and biomolecules using linear-scaling density functional theory (DFT) in a distributed memory parallel computing environment. For a >1000 atom model of the oxygenated myoglobin protein, the DDEC/c3 net charge of the adsorbed oxygen molecule is approximately -1e (in agreement with the Weiss model) using a dynamical mean field theory treatment of the iron atom, but much smaller in magnitude when using the generalized gradient approximation. For GaAs semiconducting nanorods, the system dipole moment using the DDEC/c3 NACs is about 5% higher in magnitude than the dipole computed directly from the quantum mechanical electron density distribution, and the DDEC/c3 NACs reproduce the electrostatic potential to within approximately 0.1 V on the nanorod's solvent-accessible surface. As examples of conducting materials, we study (i) a 55-atom Pt cluster with an adsorbed CO molecule and (ii) the dense solids Mo2C and Pd3V. Our results for solid Mo2C and Pd3V confirm the necessity of a constraint enforcing exponentially decaying electron density in the tails of buried atoms.
authors.affiliation: TCM Group, Cavendish Laboratory , 19 JJ Thomson Ave, Cambridge CB3 0HE, United Kingdom.
authors.forename: Louis P
authors.initials: LP
authors.lastname: Lee
authors.affiliation: Chemical & Materials Engineering Department, New Mexico State University , Las Cruces, New Mexico 88003-8001, United States.
authors.forename: Nidia Gabaldon
authors.initials: NG
authors.lastname: Limas
authors.affiliation: Department of Chemistry, Yale University , New Haven, Connecticut 06520-8107, United States.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Cole
authors.affiliation: TCM Group, Cavendish Laboratory , 19 JJ Thomson Ave, Cambridge CB3 0HE, United Kingdom.
authors.forename: Mike C
authors.initials: MC
authors.lastname: Payne
authors.affiliation: School of Chemistry, University of Southampton , Highfield, Southampton SO17 1BJ, United Kingdom.
authors.forename: Chris-Kriton
authors.initials: CK
authors.lastname: Skylaris
authors.affiliation: Chemical & Materials Engineering Department, New Mexico State University , Las Cruces, New Mexico 88003-8001, United States.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Manz