Expanding the Scope of Density Derived Electrostatic and Chemical Charge Partitioning to Thousands of Atoms

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• 作者：Louis P. Lee ; Nidia Gabaldon Limas ; Daniel J. Cole ; Mike C. Payne ; Chris-Kriton Skylaris ; Thomas A. Manz
• 刊名：Journal of Chemical Theory and Computation
• 出版年：2014
• 出版时间：December 9, 2014
• 年：2014
• 卷：10
• 期：12
• 页码：5377-5390
• 全文大小：515K
• ISSN：1549-9626

文摘

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 鈭?e (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鈥檚 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.