title: Design-atom approach for the quantum mechanical/molecular mechanical covalent boundary: a design-carbon atom with five valence electrons.
abstract: A critical issue underlying the accuracy and applicability of the combined quantum mechanical/molecular mechanical (QM/MM) methods is how to describe the QM/MM boundary across covalent bonds. Inspired by the ab initio pseudopotential theory, here we introduce a novel design atom approach for a more fundamental and transparent treatment of this QM/MM covalent boundary problem. The main idea is to replace the boundary atom of the active part with a design atom, which has a different number of valence electrons but very similar atomic properties. By modifying the Troullier-Martins scheme, which has been widely employed to construct norm-conserving pseudopotentials for density functional calculations, we have successfully developed a design-carbon atom with five valence electrons. Tests on a series of molecules yield very good structural and energetic results and indicate its transferability in describing a variety of chemical bonds, including double and triple bonds.
authors: Department of Chemistry, New York University, New York, New York 10003, USA.
authors: Chuanyun
authors: C
authors: Xiao
authors: Yingkai
authors: Y
authors: Zhang
mesh_terms: D001696:Biomechanical Phenomena; D002244:Carbon / Q000737:chemistry*; D002627:Chemistry, Physical / Q000379:methods*; D004583:Electrons; D008432:Mathematical Computing; D008956:Models, Chemical; D011789:Quantum Theory
chemical_list: D002244:Carbon